Bug 800402 - [email] UI: Show the number of unread messages in the message-list header after the folder name

You can't call this inside the callback like this unless you previously called eSync.asyncEventsAreComingDoNotResolve().  However, I think we can clean this up a little bit more anyhow. 

I would propose splitting this T.action into an action and a T.check.  The T.action and use expect_runOp() to ensure the upgrade job runs.  In the separate T.check you can use your existing expect_unread helper.  Since the action won't complete until the job completes, we know we're good.

While we're in here, I think it'd be good for us to get some coverage to make sure the glitch about upgradeFolderStoragesIfNeeded only upgrading inboxes is fixed and never comes back.  Specifically, instead of directly calling storage.upgradeIfNeeded, let's call upgradeFolderStoragesIfNeeded on the account.  Since the folder we added is not an inbox, that gets us the coverage we need without doing too much extra work.