You can either configure the appenders and log levels manually (as above), or provide a
configuration file (`log4js.configure('path/to/file.json')`) explicitly, or just let log4js look for a file called `log4js.json` (it looks in the current directory first, then the require paths, and finally looks for the default config included in the same directory as the `log4js.js` file).
An example file can be found in `test/log4js.json`. An example config file with log rolling is in `test/with-log-rolling.json`
You can also pass an object to the configure function, which has the same properties as the json versions.