explicit-json-better-error-message

To try and address a UX issue found in http://bugzilla.eng.vmware.com/show_bug.cgi?id=1002922
decided it would be a good idea to tell users why there is an authentication error.

Also with the update to the Socialcast API we need to explicitly use .json otherwise
Socialcast will return an html response.

Added ruby 2.0 as a test ruby for travis ci.