1) Switch to new TextSecureAddress addressing, rather than mixing
long-based recipient IDs into libtextsecure.
2) Get rid of RecipientFormattingException throws in calls to
RecipientFactory.
Closes#2570
1) When registering with server, indicate that the server should
store messages and send notifications.
2) Process notification GCM messages, and connect to the server
to retrieve actual message content.
