Fix for notebook in Python 3.

IPython/frontend/html/notebook/handlers.py

@@ -172,7 +172,7 b' class ZMQStreamHandler(websocket.WebSocketHandler):'
 
 class AuthenticatedZMQStreamHandler(ZMQStreamHandler):
     def open(self, kernel_id):
-        self.kernel_id = kernel_id
+        self.kernel_id = kernel_id.decode('ascii')
         self.session = Session()
         self.save_on_message = self.on_message
         self.on_message = self.on_first_message