constructor(applicationCacheDirectory, logger) {
        try {
            this._logger = logger || new ConsoleLogger(ConsoleLogger.LEVEL.Warn);
            this._applicationCacheDirectory = path.normalize(applicationCacheDirectory);
            this._versionFile = path.join(this._applicationCacheDirectory, 'version');
        } catch(error) {
            this._applicationCacheDirectory = undefined;
            this._versionFile = undefined;
        }
    }
@param {string} applicationCacheDirectory
@param {Logger} logger