Travis gemfiles and env variables refactor
Add Rails 4.2 to Travis CI
Merge pull request #496 from doorkeeper-gem/travis

Travis gemfiles and env variables refactor
Add spec for 200 response on Token revocation

Even with invalid token, as defined in
http://tools.ietf.org/html/rfc7009#section-2.2.

Fix a pending spec.
Update README to reflect changes on authentication

Further discussion in:
https://github.com/doorkeeper-gem/doorkeeper/issues/504