#2 Authentication

Implements #2, allowing for both CAS and email/password authentication. Refer to the issue for commentary; this PR includes significant changes including guest user functionality, integration tests, and more!

Issues Resolved (please check all during review):
* #2
* #694 
* #777 
* #965 
* #973
* #1018
That's fine, we can leave it as is. If FA ever changes their syntax again we should be grepping for icons anyway