Add node 7 & 8 builds (libxmljs#475)

* Add node 7 & 8 builds

Per libxmljs#474
Not sure if this is all the changes that are needed?

* Also add node 8 to appveyor.yml

* See if we can get this to build...

* Update .travis.yml

* Restore travis.yml

* Remove whitespace

* Attempt to fix node 7/8 builds on osx

* Merge npm install commands

.travis.yml

@@ -2,29 +2,23 @@ language: node_js
 os:
 - linux
 - osx
-env:
-- CXX=g++-4.8
-compiler:
-- gcc
-- clang
 node_js:
 - '0.10'
 - '0.12'
 - 4
 - 6
+- 7
+- 8
 addons:
   apt:
     sources:
     - ubuntu-toolchain-r-test
     packages:
     - g++-4.8
-    - g++-4.8
-    - g++-4.8-multilib
-    - gcc-multilib
 sudo: false
 before_install:
 - if [[ $TRAVIS_OS_NAME == "linux" ]]; then export CXX=g++-4.8; fi
-- if [[ $TRAVIS_OS_NAME == "osx" ]]; then brew install gcc48; fi
+- if [[ $TRAVIS_OS_NAME == "osx" ]]; then export CXX=clang; fi
 - $CXX --version
 
 - PUBLISH_BINARY=false
@@ -34,9 +28,7 @@ before_install:
 - case ${TRAVIS_NODE_VERSION} in 0.8*|0.10*) npm install -g npm@2 ;; esac
 - npm config set progress false
 - npm config set spin false
-- npm install node-gyp -g
-- npm install -g node-gyp
-- npm install -g node-pre-gyp
+- npm install -g node-gyp node-pre-gyp
 install:
 - npm install --build-from-source
 before_deploy:

appveyor.yml

@@ -8,6 +8,7 @@ environment:
     - nodejs_version: 5
     - nodejs_version: 6
     - nodejs_version: 7
+    - nodejs_version: 8
 
 platform:
   - x86