Initializes the file system

@param {Function?} done A callback for when initialization is complete
function initialize(done) {
    done = done || function() { };
    if (fileContents) done();

    fs.readFile(__dirname + '/../../data/filesystem.json', {
        encoding: 'utf8'
    }, function(err, data) {
        if (err) fileContents = {};
        else fileContents = JSON.parse(data);
        done();
    });
}