testing different versions of Rails using appraisal gem

@mdsol/hypermedia-team changes necessary to run different versions of rails + different versions of ruby.
In this setup: 4 specs sets would run. Later we can add Rails4.1 to Appraisal file.
@fosdev I think we can merge this, I left TODO in Gemfile to update appraisal version when fix is released.

https://travis-ci.org/mdsol/crichton/builds/26401248 - build status.