Initial integration with Travis

This PR intends to provide an intitial integration of CC with Travis
@dgirardeau you only have to sign in [Travis](https://travis-ci.org/)  and to register CC repo.

you can add more stuff in the .travis.yml file:
- [fine-grained notifications](http://docs.travis-ci.com/user/notifications/)
- and maybe [adding a bage](http://docs.travis-ci.com/user/status-images/) in the README (because it seems totally needed these days :))

On my side I will try to add a build on osx and a build with a more recent version of gcc