code: function waitforNewUpload() {
          var periodTotal = total;
          setTimeout(function () {
              if (periodTotal === total) {
                  debuglog('detect upload end');
                  end();
              }
              else {
                  debuglog('restart upload detect', periodTotal, total);
                  checkUplodingStatus(cb);
              }
          }, 50);
      }
docs: 判断20ms内是否还有新增的上传请求，如果有则回到uploding检测状态
  @return {[type]} [description]