Travis CI changes (#805)
Travis CI changes (#805)

* Add ruby-head to travis. Allow failures on ruby-head.

* Update ruby 2.2.6 to 2.2.7 for travis

* Update ruby 2.3.3 to 2.3.4 for travis

drapergem/draper,drapergem/draper,chuck-john/draper,chuck-john/draper,drapergem/draper