Googlemock

see here a first version adding googlemock framework to the unit tests.
Only drawback is that is seems to have some known issues with gcc-4.6 so I needed to change travis-ci config to use gcc 4.8 (and it will be needed on local build machines as well to build the tests).

Let me know if you like it then I'll prepare a clean pull request rebased on latest master as a single commit.

Matthias