Stop the gateway.

def stop(self):
        """Stop the gateway."""
        _LOGGER.info('Stopping gateway')
        self._disconnect()
        if self.connect_task and not self.connect_task.cancelled():
            self.connect_task.cancel()
            self.connect_task = None
        if not self.persistence:
            return
        if self._cancel_save is not None:
            self._cancel_save()
            self._cancel_save = None
        yield from self.loop.run_in_executor(
            None, self.persistence.save_sensors)