Remove one last vestige of Twisted which was missed.

Change-Id: Iee022c8200e5cd4c145e1e7bf93c0c94a8752dce
Change time parse exception type to match the one thrown.

The implementation of the time parsing was changed before last year's
competition, but the tests presumably didn't get updated. Thankfully,
while it doesn't appear to have been an issue, we were catching the
wrong thing as a result.

Change-Id: I3290b44fec012a99065ad626b53cad852f6802cf
Correct and clarify some doc comments.

Change-Id: I04c587cf86ff10dcfd9f2b9dca4c3156e0fbfce7
Fix schedule commands tests.

The times stored are full unix timestamps, so these tests need to
allow for the day information being present, and the calls being
made with those full stamps.

Change-Id: I54c35e12d24735ce37bbb4f7911e4e31b9c4d24e