update XEP-184 support by including id of request in <reveived> answer

src/common/connection_handlers.py

@@ -1515,8 +1515,8 @@ ConnectionJingle):
         not in (u'to', u'none')) or gc_contact) and mtype != 'error':
             receipt = common.xmpp.Message(to=frm, typ='chat')
             receipt.setID(msg.getID())
-            receipt.setTag('received',
-                    namespace='urn:xmpp:receipts')
+            receipt.setTag('received', namespace='urn:xmpp:receipts',
+                attrs={'id': msg.getID()})
 
             if thread_id:
                 receipt.setThread(thread_id)