Connect Authenticator to ACL/A2

Summary: Make Ushahidi_Authenticator work for resource assertions

Test Plan:
```
bin/phpunit -c application/tests/phpunit.xml application/tests/classes/Ushahidi/AuthorizerTest.php
```

Reviewers: dkobia, shadowhand

Reviewed By: shadowhand

Maniphest Tasks: T494

Differential Revision: https://phabricator.ushahidi.com/D255