moving Hongxia's changes over to this new branch, so that it's easier to sync with master
updated models
switched to standard python authentication to keep track of user analytics
added db.backend
Merge branch 'new_analytics' of https://github.com/Pinultimate/pinultimate into new_analytics
modified WebUser to support analytics (particularly total active time). implemented tap and update urls that webapp can post to for analytics.
made modifications to urls and views so that user_id does not need to be passed from client, inferred from the session.
made modifications to urls and views so that user_id does not need to be passed from client, inferred from the session.
switched from login-driven analytics to session-drive analytics