pep8: Fix E301 pep8 violations.

Fix "E301: expected (1 or 2) blank line" pep8 violations.

zerver/tornado/event_queue.py

@@ -181,6 +181,7 @@ class ClientDescriptor(object):
         self.current_client_name = client_name
         set_descriptor_by_handler_id(handler_id, self)
         self.last_connection_time = time.time()
+
         def timeout_callback():
             # type: () -> None
             self._timeout_handle = None