Update travis configuration

This PR update the travis configuration to run the test for severals php and symfony versions.

I also update the readme.
adds debug flag to setup-fabric command.
adds debug flag to setup-fabric command.
Merge pull request #138 from doppynl/debugoption

adds debug flag to setup-fabric command.
Merge pull request #137 from benjaminlazarecki/travis-configuration

Update travis configuration