Wipe out easy_thumbnails when deploying

There are different code versions in different branches with conflicting
migrations, and if there are any pyc files it makes things go very wrong (and
git doesn't manage the pycs)
Highlight daytime events in edit list.

Arbitrarily, daytime means before 6pm...
Highlight time for daytime events

Also tidy up the edit index template a bit.
Require an event template selection for new events
Make colour-code key correct for daytime events.
Merge branch 'master' into programme_redesign_grid