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) Refactor recipient class to support asynchronous loading operations.
2) Refactor recipient factory to simplify recipient access.
3) Consoliate everything into one recipient provider that is capable of
doing async lookups and intelligent caching.