Separate status for not-yet-approved-or-rejected requests

Right now, every request begins life in a "no" state and may become "yes" if anybody approves it.

Instead, I think requests should begin in a "pending" state, and require an admin to set them to "no" or "yes".

There should be no behavior difference between "pending" and "no" for now -- this feature would just be a way to distinguish between requests that nobody has looked at, and requests that somebody has looked at and rejected for now.