Use separate read and write Kombu connections

Eventlet does not like file handles to be shared among greenlets. Using
an independent connection in the listening thread addresses this
problem. (fixes #13)

socketio/kombu_manager.py

@@ -43,18 +43,24 @@ class KombuManager(PubSubManager):  # pragma: no cover
             raise RuntimeError('Kombu package is not installed '
                                '(Run "pip install kombu" in your '
                                'virtualenv).')
-        self.kombu = kombu.Connection(url)
-        self.exchange = kombu.Exchange(channel, type='fanout', durable=False)
-        self.queue = kombu.Queue(str(uuid.uuid4()), self.exchange)
-        super(KombuManager, self).__init__(channel=channel,
-                                           write_only=write_only)
+        super(KombuManager, self).__init__(channel=channel)
+        self.url = url
+        self.writer_conn = kombu.Connection(self.url)
+        self.writer_queue = self._queue(self.writer_conn)
+
+    def _queue(self, conn=None):
+        exchange = kombu.Exchange(self.channel, type='fanout', durable=False)
+        queue = kombu.Queue(str(uuid.uuid4()), exchange)
+        return queue
 
     def _publish(self, data):
-        with self.kombu.SimpleQueue(self.queue) as queue:
+        with self.writer_conn.SimpleQueue(self.writer_queue) as queue:
             queue.put(pickle.dumps(data))
 
     def _listen(self):
-        with self.kombu.SimpleQueue(self.queue) as queue:
+        reader_conn = kombu.Connection(self.url)
+        reader_queue = self._queue(reader_conn)
+        with reader_conn.SimpleQueue(reader_queue) as queue:
             while True:
                 message = queue.get(block=True)
                 message.ack()