OAuth Provider

[tsov]

• Added OAuth authentication flows via doorkeeper.
• Added assertion flow for facebook authentication.
• Added .rvmrc file
• Added some model tests for identity association
• Added some tests for identity association

[tsov]

Just thinking, maybe we should add some tests for retrieving Access Tokens? Don't merge this branch just yet!!!

[tsov]

ok, this is updated and ready to be merged. Do you have any comments?