[issue1021] Add asynchronous page update capability

Branches off of #1352. By new issue id, addresses #1336.
> One thing I'm concerned about is if people manage to confuse themselves by having two different tabs open, with different state.

`django-inplaceedit` pulls the current DB value when you edit a field, not the page value, so that kind of edit won't be a concern. And with a 5s update timer, I doubt that will be an issue.

If the concern is that the bug is removed from the set but a user can still edit it from the outdated page... well, that seems like a bit of an edge case, not sure it's much of a concern anyways. That may be something to look into in the future.