This provides a new authentication backend that generates suitable

usernames and passwords. Users will get a message on the login page as

to what username they should use. Upon logging in, they will be placed

in whatever configured review groups are provided on the authentication

settings page.
There's also a couple management commands for maintaining the server.

One for resetting the state of the demo server (which we can call

nightly), and one for dumping the database (similar to dumpdata, but

excludes anything we don't want to dump).

Been testing this locally with the demo server work I've been doing.

I saw the generated username/password on the login page, and could

successfully log in.
I reset the state of the demo server, logged in again, and saw all the

review requests in a clean state, with updated timestamps.
I've been using the dump-demo-data command for generating fixtures to

reset to.