Update the gem dependencies

 - Removing ruby 2.1 as latest ridley requires ruby >= 2.2
 - Adding ruby 2.4.0

.travis.yml

@@ -1,9 +1,9 @@
 language: ruby
 cache: bundler
 rvm:
-  - 2.3.1
-  - 2.2.3
-  - 2.1.7
+  - 2.4.0
+  - 2.3.3
+  - 2.2.6
 script:
   - bundle exec rake
   - bundle exec rake install

minimart.gemspec

@@ -22,20 +22,20 @@ Gem::Specification.new do |spec|
   spec.add_dependency 'git',          '~> 1.3'
   spec.add_dependency 'minitar',      '~> 0.5'
   spec.add_dependency 'octokit',      '~> 4.3'
-  spec.add_dependency 'redcarpet',    '= 3.3.2'
-  spec.add_dependency 'rest-client',  '~> 1.8'
-  spec.add_dependency 'ridley',       '~> 4.5'
-  spec.add_dependency 'solve',        '~> 2.0'
+  spec.add_dependency 'redcarpet',    '~> 3.4'
+  spec.add_dependency 'rest-client',  '~> 2.0'
+  spec.add_dependency 'ridley',       '~> 5.1'
+  spec.add_dependency 'solve',        '~> 3.1'
   spec.add_dependency 'thor',         '~> 0.19'
   spec.add_dependency 'tilt',         '~> 2.0'
   spec.add_dependency 'sprockets',    '~> 3.5'
   spec.add_dependency 'uglifier',     '~> 3.0'
   spec.add_dependency 'sass',         '~> 3.4'
 
   spec.add_development_dependency 'bundler', '~> 1.11'
-  spec.add_development_dependency 'rake',    '~> 11.1'
+  spec.add_development_dependency 'rake',    '~> 12.0'
   spec.add_development_dependency 'rspec',   '~> 3.4'
-  spec.add_development_dependency 'webmock', '~> 1.24'
+  spec.add_development_dependency 'webmock', '~> 2.3'
   spec.add_development_dependency 'vcr',     '~> 3.0'
   spec.add_development_dependency 'dotenv',  '~> 2.1'
 end