Bug 829520 - Folder sorting breaks the displayed folder hiearchy

f? @asutherland: So far, this just works for ActiveSync. The main thing I'm concerned about is the order of operations here. Previously, we'd get a folder creation event before the account was fully-created (and indexed by MailUniverse). Thus, I had to delay the creation of the fake Inbox by a bit. Is there a better way to do this?