Unloads the plugin

        :raises: errors.PluginUninitError

def _unload(self, ):
        """Unloads the plugin

        :raises: errors.PluginUninitError
        """
        try:
            self.uninit()
        except Exception as e:
            log.exception("Unload failed!")
            raise errors.PluginUninitError('%s' % e)
        self.__status = self.__UNLOADED