Alright. I think my credential harvester works; at least, it appears to.
Whoops. I didn't realize auth also called the callback.
OK, it's finally working. I copied Dropbox's credential logic and
modified it a bit. I need to hook it up to Makefile logic, though.

The Makefile should:
* Generate the SSL key if not present.
* Run get_db_credentials, which should check if the existing credentials work.

I also need to fix get_db_credentials so it exits when the keys are generated. It doesn't appear to do that right now.