POP doesn't supply headers in the ENVELOPE phase, so we have to
explicitly ask for, download, copy, and save small message bodies.
Fix bug in EmailProvider (it was not always detaching the body db),
leaving the DB locked in some situations.
Problems outstanding:
* POP messages are committed before they have headers, which leads
to blank entries in the UI. It might be worth tagging them and
selecting them out until they're ready to display.
* Inefficient because we're reloading the message from the provider on
each pass, instead of hanging onto it and updating it.
* Not marking "complete" yet because we aren't handling attachments
or inline images yet. So we keep on reloadin'.
5f4dbd6438