Update oauth2-server-php library
Add @oauth2Skip hook to feature tests to automatically add auth header

* Creates an auth token during 'BeforeFeature' stage
* Adds the header in 'BeforeScenario' stage
* Add the oauth2Skip tag to all tests except oauth.feature
Fixing errors in tests after merge: change response status to guzzle status
Fix error from merge: Add locale post in oauth fixture
Fix handling of form_id in posts api: no PHP error if missing
Formatting fix to RestContext