Allow mhimap-fetch to be embedded

This will end up embedded directly into mhng-daemon in a bit.
Add "mhng-daemon", a synchronization daemon

The general idea here is that I want to have something that runs in
the background so I can pass synchronization requests intho the
background.  This is nice because it allows me to have a single point
that fires off synchronization jobs.  While this shouldn't be
necessary, it's just a bit cleaner to track everything down.

Right now this doesn't really do a whole bunch because nothing talks
to it...
Have "mhng-rmm" trigger a sync

The idea here is that if I remove a message then I want it pushed to
the server.
Have "mhng-show" trigger a sync

This can change the read status of messages, so it needs to force a
sync.