Update democracy.com balance
Implement sharding counter scheme for computing the total donations.

https://developers.google.com/appengine/articles/sharding_counters

This change increments the counters, and stores all the pledges with
model_version=2 for tracking. We don't actually use the counters
yet. Once this is live and no more pledges are coming in without
model_version>=2, we'll count the total donations for pledges not
included in the counters, and manually add that.
Merge pull request #40 from MayOneUS/sharded-counter

Implement sharding counter scheme for computing the total donations.
Actually use the sharded counters in total, and add information to the admin page to see if there are discrepancies.
Update democracy.com balance
Update GA to analytics.js.