Handle resource server errors with correct HTTP status, fixes T314

Summary:
- require v3.2.2 of League OAuth2 Server
- add handler for resource server errors
- update tests to match spec: http://tools.ietf.org/html/rfc6750#section-3.1

Test Plan:
```
bin/update
bin/behat -f progress -c application/tests/behat.yml application/tests/features/api.oauth.feature
```

Reviewers: rjmackay, eyedol, dkobia

Reviewed By: dkobia

Subscribers: bodacea, srutto

Maniphest Tasks: T314

Differential Revision: https://phabricator.ushahidi.com/D232