Add special case handling for draft messages so that if a Draft is
updated via an event it is correctly updated on the IMAP client via a
the new `imap.MessageUpdated event`.
This patch also updates Gluon to the latest version.
Only delete messages when unlabeled from trash/spam if they only exists
in All Mail and (spam or trash).
This patch also ports delete_from_trash.feature and use status rather
than fetch to count messages in a mailboxes.
