remove events after they "expire"

Currently customers can buy tickets for events that happened before today's date
We should not be showing there at all, and should be removing them from the database

[danyakarras]

but maybe don't completely remove them so that we can still do random queries?
Orrrrrrr this might be more work, but could we have a "past events" table that we could use to get stats from? That could be too much work though. Let's just display events that are after today's date, and just keep the rest there but don't ever show them..?