added .travis.yml

I was surprised to see that you do not leverage travis ci yet. So I just quickly set it up.
Of course this also requires enabling the travis commit hook on travis-ci.org for this repository.

Currently working through some of the dependencies to also make the tests pass with dev-master.

https://github.com/Abhoryo/APYJsFormValidationBundle/pull/46
https://github.com/willdurand/BazingaExposeTranslationBundle/pull/65
https://github.com/BeSimple/BeSimpleSoap/pull/14

but this should not stop merging this PR :)