Cleanup ruby code via rubocop

This commit will add code cleanup as corrected
and alerted by rubocop. It also adds rules to
execute rubocop on Travis.

.travis.yml

@@ -28,5 +28,7 @@ matrix:
   - rvm: 2.1.9
     bundler_args: --without system_tests
     env: PUPPET_GEM_VERSION="~> 4.0"
+  - rvm: 2.1.9
+    script: bundle exec rake rubocop
 notifications:
   email: false