Local notification rules

Update android client local notifications to follow these rules:

1. Only send a notification if it is a UUID/major/minor combination that is part of the scavenger hunt, and it is one that had not been found yet in the hunt
2. Don't ever send two notifications in under 60 seconds
3. If the same beacon that you already sent a notification for sticks around (or goes in and out) don't send another notification for the same one for at least five minutes