Add pledges to events so pledges can have events
Add update events to pledges
Log update events when pledges are updated
Add ability to cancel pledges (model layer)

Canceled pledges don't get reminders and (soon) won't show up in the app
where pledges currently show.
Add ability to cancel a pledge (controller layer)

Also, canceled pledges now don't show up on the profile page or donate
page.
Update/fix some broken fixture-based tests
Add a way to make a new pledge

If the current user is a donor but doesn't have a current pledge, we
show a link to the new-pledge form and let them make a new one.
Add pledge reference to donations

This is to track which donations went with which pledges, so that we
know when a given pledge has been fulfilled.
Show previous donation count for current pledge

On the donate page, in the sidebar.
Add support for ended pledges

Ended pledges are pledges whose time is up. Nothing actually ends
pledges yet, but soon we'll do that automatically.
Automatically end pledges and mail users

Ends active pledges after the PLEDGE_PERIOD of 1 month, emailing the
user with a summary of how they did and encouraging them to make a new
pledge.
Fix typo
Send users to donate page after pledging

Makes more sense than the homepage