Tokens/revoke

Revokes a token by calling DELETE /oauth/token. Assuming the use case is for logging out of an application and not to use calback to manage other tokens/other applications tokens of the same user.

 - No Parameters needed, token used to authenticate request revokes itself.
 - This approach avoids having to check POST parameters to match token's application_id, token
 -- Otherwise one could use a token for one application and possibly revoke a token for a second application, or use one token to revoke a different token.