Add GMock to .travis.yml (#1226)

* Add GMock to .travis.yml

* Add ls to .travis.yml

* Install google-mock differently

* Require sudo

* Revert last 3 commits

* Remove build commands for google-mock

These are not needed in precise, as it still ships prebuilt libraries

.travis.yml

@@ -7,6 +7,7 @@ addons:
  apt:
   packages:
   - libgtest-dev
+  - google-mock
  coverity_scan:
    project:
      name: Yakindu/statecharts