Merge pull request #217 from dsquier/develop

Implement ScopeInterface for PDO, Redis
Updated docblocks for RefreshTokenInterface.php

`user_id` field was missing for set/get refresh token methods.
Merge branch 'develop' of https://github.com/bshaffer/oauth2-server-php into develop
fixes #224 - makes  and  protected properties
Merge pull request #223 from svycka/patch-1

Updated docblocks for RefreshTokenInterface.php
better support for scopes in PDO
Merge branch 'develop' of https://github.com/bshaffer/oauth2-server-php into develop