jp: jp asyncio port:

/!\ this commit is huge. Jp is temporarily not working with `dbus` bridge /!\

This patch implements the port of jp to asyncio, so it is now correctly using the bridge
asynchronously, and it can be used with bridges like `pb`. This also simplify the code,
notably for things which were previously implemented with many callbacks (like pagination
with RSM).

During the process, some behaviours have been modified/fixed, in jp and backends, check
diff for details.

sat/plugins/plugin_sec_otr.py

@@ -108,7 +108,7 @@ class Context(potr.context.Context):
             message data when an encrypted message is going to be sent
         """
         assert isinstance(self.peer, jid.JID)
-        msg = msg_str
+        msg = msg_str.decode('utf-8')
         client = self.user.client
         log.debug("injecting encrypted message to {to}".format(to=self.peer))
         if appdata is None:
@@ -530,7 +530,7 @@ class OTR(object):
             )  # FIXME: temporary and unsecure, must be changed when frontends
                #        are refactored
         otrctx = client._otr_context_manager.getContextForUser(to_jid)
-        query = otrctx.sendMessage(0, "?OTRv?")
+        query = otrctx.sendMessage(0, b"?OTRv?")
         otrctx.inject(query)
 
     def _otrSessionEnd(self, menu_data, profile):