Bluetooth-test and Message structure improvements

These commits get us back to bluetooth-test functionality, with some additional functionality (e.g. Let Me In/FindNewFans button).  This implements the new discovery style (though not the whole new discovery process), and supports discovering multiple fans at once.  Tested using my Nexus4 and Reid's test Galaxy Nexus...there is some bad connection latency when there are a lot of other non-fanClub bluetooth devices nearby, and we need some way of detecting when a socket is dropped, but otherwise it tested fine.