Cleanup & project automation

Some basic Django hygiene and automation, along with some code cleanup. Best viewed with whitespace diffs suppressed, and best reviewed commit-by-commit.

Nice start, @bdyn!
This a Makefile - it tells the `make` command what sorts of things you'd like to automate in this project. (`make` comes with the XCode Mac app, which homebrew probably forced you to install.)

I'll explain the immediately important parts of this, but this is definitely the most complicated portion of this diff. If you're not interested in the extra complexity, just delete the file after you merge this pull request.