Add a mechanism to sync user data with dev app.

It strips all sensitive data from the set, and syncs in a cron
job which runs every hour.
Make sync requests use json instead of form.

I also finally fixed the whole dev mode detection mess.
More security changes.

- Make the datasync post request only work on the dev server.
Add first-time syncing and more logging.

Now it will sync all the membership models if it determines that
this is the first time it is running.
Make it nullify the hash property as well.
Add daniel's syncing stuff in.

Conflicts:
	membership.py