Move GetTotalHandler into handlers.py, add tests.

Also updates the memcache entry for the total at pledge time, so the
progress bar should update pretty much instantly!
Fix broken privacy link
Stop the spinner on error
Use new /r/total handler in embed.html.
Add pledge_type field to Pledge.

Indicates whether the pledge is conditional or not. Currently, it's
always conditional.
Merge branch 'master' of https://github.com/MayOneUS/app-engine into email-signup

Conflicts:
	backend/handlers.py
	backend/util.py
redid changes after merge conflict