Setup logging via CLI options

        If `--background` -- set INFO level for root logger.
        If `--logdir` -- set logging with next params:
            default Luigi's formatter,
            INFO level,
            output in logdir in `luigi-server.log` file

def _cli(cls, opts):
        """Setup logging via CLI options

        If `--background` -- set INFO level for root logger.
        If `--logdir` -- set logging with next params:
            default Luigi's formatter,
            INFO level,
            output in logdir in `luigi-server.log` file
        """
        if opts.background:
            logging.getLogger().setLevel(logging.INFO)
            return True

        if opts.logdir:
            logging.basicConfig(
                level=logging.INFO,
                format=cls._log_format,
                filename=os.path.join(opts.logdir, "luigi-server.log"))
            return True

        return False