start = function () {
        daemon.daemonize(log_file, lock_file, function (err) {
            if (err) return status('Error starting daemon: ' + err, 'error');
            callback();
        });
    }
A method for creating and controlling a node.io daemon.

`arg` can be:
     start = daemonizes the process
     stop  = stops the daemon if it is running
     restart = alias for stop -> start
     pid = outputs the daemon's PID if it is running
     log = outputs the daemon's log file (stdout & stderr)

@param {String} arg
@param {Function} callback
@api public