Split up project details into multiple pages.

This makes the project views a bit less muddled in what they do, and
gives us room to add another tab for managing the command schedule.
Add scheduled commands.

Adds a view for listing and creating scheduled commands, which are 
commands that run at a specified interval automatically. A management
command processes all scheduled commands and executes any commands that
are due to run; this command should be run by a cronjob at the lowest
interval rate (15 minutes).
Tests! Also fixing a few docstrings.