ask users if they want their pledges to be anonymous

this change adds a checkbox to every pledge that asks users
if they want their pledge to be anonymous (for use with later
features in this changeset stack)
endpoint to return pledge-page pledgers

this returns a list of pledgers that pledged through a specific
page. this way, team owners know who to thank, and we can possibly
enable this for the general public on the team page, instead of
just team owners knowing

this is just a json endpoint with no ui
keep track of team totals

once this commit is deployed, we're going to need to run
TeamTotal.get(team_id) for every team, before we can be sure
there's a TeamTotal for every team

this change is necessary for the leaderboard.
leaderboard handler

this change maintains a top-n list of teams based on amount raised.

this is just a json endpoint and has no ui
okay, testing is definitely necessary before deploy
make anonymous field not required, bugfix
fix initial team total calculation with existing indexes
Merge pull request #90 from MayOneUS/team_pledge_api

Team pledge api