Fixed: file appenders don't work in Windows.

In Windows, file mode '0644' will create the file in read-only mode.
Also, the UV source code says that, for that reason, in Windows, file mode 0666 should always be used.
See: http://stackoverflow.com/questions/22401319/write-logs-in-file-using-log4js-in-node-js/
See: http://stackoverflow.com/questions/23329451/node-file-modes-on-windows