Allow loading just a single scheduling check.

Ideally we would do lots of magic ajax stuff, but this was quicker and easier.
You can go to /manage///scheduling_check_list and click on a check to view just
that one.

Please don't merge this yet; I want to make some improvements after scheduling weekend.  I'm putting it here so I remember, and so if anyone has comments now they can make them.
What's going on with this line?