Added --coverage-text to travis

FOSRestBundle has this in their travis file: https://github.com/FriendsOfSymfony/FOSRestBundle
You then get nice reports in travis log like this: https://travis-ci.org/FriendsOfSymfony/FOSRestBundle/jobs/16047555
The idea is that it'll be easier to strive for 100% code coverage with a nice report like that ;)