Restore OAuth scope checking, add test, fixes T687

Summary:
Lost scope checking while working on T314, this restores it and adds a test
to prevent further regressions.

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

Reviewers: rjmackay

Reviewed By: rjmackay

Subscribers: aMoniker, eyedol, rjmackay

Maniphest Tasks: T687

Differential Revision: https://phabricator.ushahidi.com/D324