Improve logic for seleting watched games

Update the user model to contain sportsWatched, and from that, games
watched within a sport. Provide a fix to account for the "_id" sent by
Backbone and error'd by Mongo.
Skip session validation check for login view

If the route is login, skip the before filter check
Move games into archived, available, and future

With games watched added to the user, we can now move games into three
categories: archived (watched), available, and future (both
un-watched). Update the UI to reflect this, and allow selecting a game
as watched only if it's available.