core (xmpp): send initial presence only after all profileConnected have been treated:

presence is now sent after profileConnected methods are done, this avoid to have to deal with synchronisation in connection event.
For instance, PEP events should not be sent before presence is sent, so profileConnected methods can assume PEP events are not
done yet, and do needed initialisation using async method if necessary.

This has been done to avoid overcomplicated synchronisation in XEP-0384 plugin (network calls are needed to initialise session,
but PEP events need an initialised session to be treated).

sat/core/xmpp.py

@@ -196,6 +196,9 @@ class SatXMPPEntity(object):
         )  # FIXME: we should have a timeout here, and a way to know if a plugin freeze
         # TODO: mesure launch time of each plugin
 
+        # we finally send our presence
+        entity.presence.available()
+
     def getConnectionDeferred(self):
         """Return a deferred which fire when the client is connected"""
         return self.conn_deferred
@@ -678,7 +681,6 @@ class SatXMPPClient(SatXMPPEntity, wokkel_client.XMPPClient):
 
     def _finish_connection(self, __):
         self.roster.requestRoster()
-        self.presence.available()
         super(SatXMPPClient, self)._finish_connection(__)