[ZEPPELIN-2761] - Neo4j Interpreter

### What is this PR for?
This contribution would to introduce Neo4j Cypher intepreter and at the same time provides base APIs that enable other graph databases (or graph framworks such as GraphX or Giraph).

### What type of PR is it?
[Feature]

### Todos
* [x] - Provide base APIs to manage graph results (under: org.apache.zeppelin.interpreter.graph.*)
* [x] - Create the Neo4j intepreter

### What is the Jira issue?
[[ZEPPELIN-2761]](https://issues.apache.org/jira/browse/ZEPPELIN-2761)

### How should this be tested?
Donwload and execute [Neo4j](https://neo4j.com/download/?ref=home) v3.x, you can also pull a [Docker image](https://neo4j.com/developer/docker/).

In order to execute test cases, if you are running Java 7, you need to also provide an environment variable telling the tests where to find Java 8, because Neo4j-the-database needs it to run.
```bash
export NEO4J_JAVA=<path/to/java/home>
```

Use this statement to create a dummy dataset
```bash
%neo4j
UNWIND range(1,100) as id
CREATE (p:Person {id:id, name: "Name " + id, age: id % 3}) WITH collect(p) as people
UNWIND people as p1
UNWIND range(1,10) as friend
WITH p1, people[(p1.id + friend) % size(people)] as p2
CREATE (p1)-[:KNOWS {years: abs(p2.id - p2.id)}]->(p2)
```

Then you can write some simple queries like:
```bash
%neo4j
MATCH (p:Person)-[r:KNOWS]-(p1:Person)
RETURN p, r, p1
LIMIT 10;
```

```bash
%neo4j
MATCH (p:Person)-[r:KNOWS]-(p1:Person)
RETURN p.id AS ID_A, p.name AS NAME_A, r.years AS YEARS, p1.id AS ID_B, p1.name AS NAME_B
LIMIT 20;
```

### Video
![zeppelin query examples](https://user-images.githubusercontent.com/1833335/28041473-daaa1f02-65c9-11e7-9445-c45478669d66.gif)

### Questions:
* Does the licenses files need update? **Yes**
* Is there breaking changes for older versions? **No**
* Does this needs documentation? **Yes**

Author: conker84 <[email protected]>

Closes apache#2478 from conker84/master and squashes the following commits:

5fb97ce [conker84] review by felixcheung 18/09
1e3d611 [conker84] Review by felixcheung (09/08)
aaf618e [conker84] Review by 1ambda 26/07
b5c2c66 [conker84] Added docs
9eb568d [conker84] Final behavior after discussion
2f88e98 [conker84] Moved business logic to the connection manager
8e4690e [conker84] Create connection manager class
35b4e29 [conker84] First commit

docs/_includes/themes/zeppelin/_navigation.html

@@ -137,6 +137,7 @@
                 <li><a href="{{BASE_PATH}}/interpreter/lens.html">Lens</a></li>
                 <li><a href="{{BASE_PATH}}/interpreter/livy.html">Livy</a></li>
                 <li><a href="{{BASE_PATH}}/interpreter/markdown.html">Markdown</a></li>
+                <li><a href="{{BASE_PATH}}/interpreter/neo4j.html">Neo4j</a></li>
                 <li><a href="{{BASE_PATH}}/interpreter/pig.html">Pig</a></li>
                 <li><a href="{{BASE_PATH}}/interpreter/postgresql.html">Postgresql, HAWQ</a></li>
                 <li><a href="{{BASE_PATH}}/interpreter/r.html">R</a></li>

docs/index.md

@@ -142,6 +142,7 @@ limitations under the License.
   * [Lens](./interpreter/lens.html)
   * [Livy](./interpreter/livy.html)
   * [markdown](./interpreter/markdown.html)
+  * [Neo4j](./interpreter/neo4j.html)
   * [Pig](./interpreter/pig.html)
   * [Postgresql, HAWQ](./interpreter/postgresql.html)
   * [Python](./interpreter/python.html)

docs/interpreter/neo4j.md

@@ -0,0 +1,117 @@
+---
+layout: page
+title: "Neo4j Interpreter for Apache Zeppelin"
+description: "Neo4j is a native graph database, designed to store and process graphs from bottom to top."
+group: interpreter
+---
+<!--
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+-->
+{% include JB/setup %}
+
+# Neo4j Interpreter for Apache Zeppelin
+
+<div id="toc"></div>
+
+## Overview
+[Neo4j](https://neo4j.com/product/) is a native graph database, designed to store and process graphs from bottom to top.
+
+
+![Neo4j - Interpreter - Video]({{BASE_PATH}}/assets/themes/zeppelin/img/docs-img/neo4j-interpreter-video.gif)
+
+## Configuration
+<table class="table-configuration">
+  <tr>
+    <th>Property</th>
+    <th>Default</th>
+    <th>Description</th>
+  </tr>
+  <tr>
+    <td>neo4j.url</td>
+    <td>bolt://localhost:7687</td>
+    <td>The Neo4j's BOLT url.</td>
+  </tr>
+  <tr>
+    <td>neo4j.auth.type</td>
+    <td>BASIC</td>
+    <td>The Neo4j's authentication type (NONE, BASIC).</td>
+  </tr>
+  <tr>
+    <td>neo4j.auth.user</td>
+    <td>neo4j</td>
+    <td>The Neo4j user name.</td>
+  </tr>
+  <tr>
+    <td>neo4j.auth.password</td>
+    <td>neo4j</td>
+    <td>The Neo4j user password.</td>
+  </tr>
+  <tr>
+    <td>neo4j.max.concurrency</td>
+    <td>50</td>
+    <td>Max concurrency call from Zeppelin to Neo4j server.</td>
+  </tr>
+</table>
+
+<center>
+  ![Interpreter configuration]({{BASE_PATH}}/assets/themes/zeppelin/img/docs-img/neo4j-config.png)
+</center>
+
+
+## Enabling the Neo4j Interpreter
+In a notebook, to enable the **Neo4j** interpreter, click the **Gear** icon and select **Neo4j**.
+
+## Using the Neo4j Interpreter
+In a paragraph, use `%neo4j` to select the Neo4j interpreter and then input the Cypher commands.
+For list of Cypher commands please refer to the official [Cyper Refcard](http://neo4j.com/docs/cypher-refcard/current/)
+
+```bash
+%neo4j
+//Sample the TrumpWorld dataset
+WITH
+'https://docs.google.com/spreadsheets/u/1/d/1Z5Vo5pbvxKJ5XpfALZXvCzW26Cl4we3OaN73K9Ae5Ss/export?format=csv&gid=1996904412' AS url
+LOAD CSV WITH HEADERS FROM url AS row
+RETURN row.`Entity A`, row.`Entity A Type`, row.`Entity B`, row.`Entity B Type`, row.Connection, row.`Source(s)`
+LIMIT 10
+```
+
+The Neo4j interpreter leverages the [Network display system](../usage/display_system/basic.html#network) allowing to visualize the them directly from the paragraph.
+
+
+### Write your Cypher queries and navigate your graph
+
+This query:
+
+```bash
+%neo4j
+MATCH (vp:Person {name:"VLADIMIR PUTIN"}), (dt:Person {name:"DONALD J. TRUMP"})
+MATCH path = allShortestPaths( (vp)-[*]-(dt) )
+RETURN path
+```
+produces the following result_
+![Neo4j - Graph - Result]({{BASE_PATH}}/assets/themes/zeppelin/img/docs-img/neo4j-graph.png)
+
+### Apply Zeppelin Dynamic Forms
+You can leverage [Zeppelin Dynamic Form](../usage/dynamic_form/intro.html) inside your queries. This query:
+
+```bash
+%neo4j
+MATCH (o:Organization)-[r]-()
+RETURN o.name, count(*), collect(distinct type(r)) AS types
+ORDER BY count(*) DESC
+LIMIT ${Show top=10}
+```
+
+produces the following result:
+![Neo4j - Zeppelin - Dynamic Forms]({{BASE_PATH}}/assets/themes/zeppelin/img/docs-img/neo4j-dynamic-forms.png)
+

neo4j/pom.xml

@@ -0,0 +1,144 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!--
+  ~ Licensed to the Apache Software Foundation (ASF) under one or more
+  ~ contributor license agreements.  See the NOTICE file distributed with
+  ~ this work for additional information regarding copyright ownership.
+  ~ The ASF licenses this file to You under the Apache License, Version 2.0
+  ~ (the "License"); you may not use this file except in compliance with
+  ~ the License.  You may obtain a copy of the License at
+  ~
+  ~    http://www.apache.org/licenses/LICENSE-2.0
+  ~
+  ~ Unless required by applicable law or agreed to in writing, software
+  ~ distributed under the License is distributed on an "AS IS" BASIS,
+  ~ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+  ~ See the License for the specific language governing permissions and
+  ~ limitations under the License.
+  -->
+
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/maven-v4_0_0.xsd">
+  <modelVersion>4.0.0</modelVersion>
+
+  <parent>
+    <artifactId>zeppelin</artifactId>
+    <groupId>org.apache.zeppelin</groupId>
+    <version>0.8.0-SNAPSHOT</version>
+    <relativePath>..</relativePath>
+  </parent>
+
+  <groupId>org.apache.zeppelin</groupId>
+  <artifactId>zeppelin-neo4j</artifactId>
+  <packaging>jar</packaging>
+  <version>0.8.0-SNAPSHOT</version>
+  <name>Zeppelin: Neo4j interpreter</name>
+
+  <properties>
+  	<neo4j.driver.version>1.4.3</neo4j.driver.version>
+  	<test.neo4j.kernel.version>3.2.3</test.neo4j.kernel.version>
+  	<neo4j.version>3.2.3</neo4j.version>
+  	<jackson.version>2.8.9</jackson.version>
+  </properties>
+
+  <dependencies>
+    <dependency>
+      <groupId>${project.groupId}</groupId>
+      <artifactId>zeppelin-interpreter</artifactId>
+      <version>${project.version}</version>
+      <scope>provided</scope>
+    </dependency>
+
+    <dependency>
+      <groupId>com.fasterxml.jackson.core</groupId>
+      <artifactId>jackson-databind</artifactId>
+      <version>${jackson.version}</version>
+    </dependency>
+
+    <dependency>
+      <groupId>org.neo4j.driver</groupId>
+      <artifactId>neo4j-java-driver</artifactId>
+      <version>${neo4j.driver.version}</version>
+    </dependency>
+
+    <dependency>
+      <groupId>org.slf4j</groupId>
+      <artifactId>slf4j-api</artifactId>
+    </dependency>
+
+    <dependency>
+      <groupId>org.slf4j</groupId>
+      <artifactId>slf4j-log4j12</artifactId>
+    </dependency>
+
+    <dependency>
+      <groupId>junit</groupId>
+      <artifactId>junit</artifactId>
+      <scope>test</scope>
+    </dependency>
+
+    <dependency>
+      <groupId>org.neo4j.test</groupId>
+      <artifactId>neo4j-harness</artifactId>
+      <version>${neo4j.version}</version>
+      <scope>test</scope>
+    </dependency>
+  </dependencies>
+
+  <build>
+    <plugins>
+      <plugin>
+        <artifactId>maven-enforcer-plugin</artifactId>
+        <version>1.3.1</version>            
+        <executions> 
+          <execution> 
+            <id>enforce</id> 
+            <phase>none</phase> 
+          </execution>
+        </executions>
+      </plugin>
+
+      <plugin>
+        <artifactId>maven-dependency-plugin</artifactId>
+        <version>2.8</version>
+        <executions>
+          <execution>
+            <id>copy-dependencies</id>
+            <phase>package</phase>
+            <goals>
+              <goal>copy-dependencies</goal>
+            </goals>
+            <configuration>
+              <outputDirectory>${project.build.directory}/../../interpreter/neo4j</outputDirectory>
+              <overWriteReleases>false</overWriteReleases>
+              <overWriteSnapshots>false</overWriteSnapshots>
+              <overWriteIfNewer>true</overWriteIfNewer>
+              <includeScope>runtime</includeScope>
+            </configuration>
+          </execution>
+          <execution>
+            <id>copy-artifact</id>
+            <phase>package</phase>
+            <goals>
+              <goal>copy</goal>
+            </goals>
+            <configuration>
+              <outputDirectory>${project.build.directory}/../../interpreter/neo4j</outputDirectory>
+              <overWriteReleases>false</overWriteReleases>
+              <overWriteSnapshots>false</overWriteSnapshots>
+              <overWriteIfNewer>true</overWriteIfNewer>
+              <includeScope>runtime</includeScope>
+              <artifactItems>
+                <artifactItem>
+                  <groupId>${project.groupId}</groupId>
+                  <artifactId>${project.artifactId}</artifactId>
+                  <version>${project.version}</version>
+                  <type>${project.packaging}</type>
+                </artifactItem>
+              </artifactItems>              
+            </configuration>
+          </execution>
+        </executions>
+      </plugin>
+    </plugins>
+  </build>
+
+</project>