Improve the Auth - autologin

This turned into more of a project than I expected:

* auto logs in a UNL user if the `unl_sso` cookie was found.
* both the manager and front end implemented their own auth, so I centralized it
* I ran into issues with the testing environment (headers already sent, etc), so I made a mock auth provider for tests

Good question.  I will check the embed code.