code: function readFilePromise(filename) {
    var deferred;
  
    deferred = Q.defer();
  
    fs.readFile(filename, 'utf-8', function (err, contents) {
      if (err) {
        if (err.code === 'ENOENT') {
          debug(err.code + ': ' + filename);
          return deferred.resolve();
        }
        debug(err + ' ' + filename);
        // TODO: better error handling
        deferred.reject(err);
      } else {
        debug('read ' + filename);
        deferred.resolve(contents);
      }
    });
  
    return deferred.promise;
  }
docs: Promise to load a file's contents
  
  @param {string} filename The file to load
  @return {Promise.<string>} The file's contents