Remove Devise

[dmolesUC]

Devise is overkill for the minimal authentication/authorization we need (just limiting access to restricted records).

It should be possible to operate Blacklight without it (see docs, "Install and Use (with a custom user authentication system)"), and replace it with something similar to what we do in Framework and UC BEARS.

Relevant UCBEARS code:

• SessionsController
• ApplicationController#current_user
• User

It's possible that if we disable the Blacklight bookmark functionality we can get away without a User model, and in fact without a database -- we should look into that as well, but if it proves too complicated we should break that out into a separate issue.