Updated Travis CI configuration to also test against PHP 5.6 and HHVM.
Hopefully fixed the Travis CI configuration.
Merge branch 'develop' of github.com:ManneW/HipChatBundle

* 'develop' of github.com:ManneW/HipChatBundle:
  Hopefully fixed the Travis CI configuration.
  Updated Travis CI configuration to also test against PHP 5.6 and HHVM.