Differentiate between asynchronous and synchronous ones. Asynchronous
are the ones where the invocation order may not be the same as the order
in which the stanzas arrived.
Since it's no longer guaranteed that when a unit test calls
processPacket(stanza)
the stanza will be completely processed when the call returns, it was
necessary to extend the unit tests (mostly Roster and ChatManager) with
a packet listener that waits for his invocation. Since we now also use
LinkedHashMaps as Map for the packet listeners (SMACK-531, SMACK-424),
adding a packet listeners as last also means that it will be called as
last. We exploit this behavior change now in the unit tests.
Rename 'recvListeners' to 'syncRecvListeners' in AbstractXMPPConnection.
Rename 'rosterInitialized' to 'loaded' in Roster.
Add Roster.isLoaded().
Reset 'loaded' to false in
Roster.setOfflinePresencesAndResetLoaded() (was setOfflinePresences()).
Fixes SMACK-583, SMACK-532, SMACK-424
