Fixed text output when voting on kegs.  Fixes #36
Can no longer submit duplicate kegs when one has been suggested

already, but not purchased.  Fixes #31
Gracefully expire Untappd tokens when they are no longer valid

Hackish way to do it, but it will work...for now
Use auto_add_now instead of auto_add for timestamp fields

For #35: Migrations before this will still cause suggestions
to update to the time of migration.