Merge branch 'hotfix/45'

Close #45
pdo options support.
allow passing through an array of PDO options via the 'options' config key.
@see https://github.com/bshaffer/oauth2-server-php/pull/396 pull request which adds support for pdo options to oauth2-server-php's pdo storage
Merged upstream master.
Added the unit test for PDO db options
Merge branch 'brettmc-feature/allow-pdo-options' into develop