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

Ideally this would be a gateway auth only, otherwise we are _requiring_ authentication for every page with the presence of a cookie that can be controlled by any UNL domain.

Does this effect the embed code in any way? If a person is forced to login just to watch a piece of media embedded on a site, that will certainly be a UX failure.