Setup logging via CLI params and config.

def setup(cls,
              opts=type('opts', (), {
                  'background': None,
                  'logdir': None,
                  'logging_conf_file': None,
                  'log_level': 'DEBUG'
              })):
        """Setup logging via CLI params and config."""
        logger = logging.getLogger('luigi')

        if cls._configured:
            logger.info('logging already configured')
            return False
        cls._configured = True

        if cls.config.getboolean('core', 'no_configure_logging', False):
            logger.info('logging disabled in settings')
            return False

        configured = cls._cli(opts)
        if configured:
            logger = logging.getLogger('luigi')
            logger.info('logging configured via special settings')
            return True

        configured = cls._conf(opts)
        if configured:
            logger = logging.getLogger('luigi')
            logger.info('logging configured via *.conf file')
            return True

        configured = cls._section(opts)
        if configured:
            logger = logging.getLogger('luigi')
            logger.info('logging configured via config section')
            return True

        configured = cls._default(opts)
        if configured:
            logger = logging.getLogger('luigi')
            logger.info('logging configured by default settings')
        return configured