stop OpenThread stack

        Returns:
            True: successful to stop OpenThread stack and thread interface down
            False: fail to stop OpenThread stack

def __stopOpenThread(self):
        """stop OpenThread stack

        Returns:
            True: successful to stop OpenThread stack and thread interface down
            False: fail to stop OpenThread stack
        """
        print 'call stopOpenThread'
        try:
            if self.__sendCommand('thread stop')[0] == 'Done':
                return self.__sendCommand('ifconfig down')[0] == 'Done'
            else:
                return False
        except Exception, e:
            ModuleHelper.WriteIntoDebugLogger("stopOpenThread() Error: " + str(e))