Create mappers and entities for oauth tokens.
Implement a way to retrieve the actual token string from the UserToken object.
Add logout method to OAuth controller.

Expire access token immediately on logout.
Expire refresh token upon logout.
Add use statement for OutOfBoundsException.
Merge branch 'master' into expire-tokens-on-logout

Conflicts:
	src/Synapse/Controller/OAuthController.php
	src/Synapse/Provider/OAuth2ServerServiceProvider.php
Merge pull request #30 from synapsestudios/expire-tokens-on-logout

Log out should immediately expire oauth token