Add comments to models in expected events model

Since we have so many now, we want to make sure we know exactly what each one is doing, so we're putting comments above them for easy reference.
Install TimeCop
Fix days of the week so they correctly correspond to numbers
Add ExpectedEvent#active_today?
Change deadline method to include active_today? method
Add tests for active_today?

using TimeCop
Remove weekday_checker method

Replaced with active_today?