Proposed Cleanup

So. The MIT server is running off of pull-645-rebase. People made tweaks and did dev work on the server, which I committed to a child branch, dirty-server. This pull request attempts to bring us back in line with main, with some MIT-specific changes omitted (in particular, the splash-class-registrations@ hack will stay on the server, as will django-debug-toolbar until it is reviewed further). Is this acceptable?

The bulk of the changes below seem minor. Everything runs on my dev server, and I've tested some functionality.

This pull request includes #715 inside of commit d281a06.