Allow non-beer-consuming Monkey Bar attendees to "check-in" using a card

[crcastle]

Feature request from Kelley:

Allow a user to scan their card, not pour, and get counted as a "check-in" at the party.

I think we could detect when this happens by waiting for a flow event after a scan. If there is no pour event within a certain number of seconds (like 5), count the event as a "check-in". Each pour event should also count as a "check-in".

Non-pour check-ins should be listed in the recent activity and tweeted like pours. In the future, we could allow integration with Foursquare check-ins (which I'm not a fan of but I know others are). Getting even more meta, instead of implementing Foursquare specifically we could implement a generic post-check-in callback. This would trigger a POST request to a user-specified URL after each keg.io check-in or pour. This would then allow others to extend the functionality of keg.io and link check-in events to other services. (I've created this as a separate new feature request: issue #31)

This would:

• allow others who don't drink beer to be included in the keg.io fun
• give us nice stats on monkey bar party attendance.