Remove Redis Queue

[sebasptsch]

At the moment for queueing tasks like user checkout when an event is over there's a Redis queue that queue's a new job when the event ends.

I want to get rid of this so that the system doesn't require Redis. My solution to this is when someone checks in, set their checkout time to the same value as the checkin time. That way if they don't check out the difference between those two times is zero. Allow users to checkout after an event is over.