This test will generate a basic Rails application, include Paperclip into Gemfile, and call basic `has_attached_file` in the model. This will make sure that we're not messing up any of the configuration and integration for our gem and the Rails framework.
It seems like that JRuby on travis-ci is broken, so we shouldn't test against it to reduce the false-positive result. I've run the test locally, and it passed just fine. : http://travis-ci.org/#!/thoughtbot/paperclip/builds/79181 : https://gist.github.com/299686b412f9ad878e16