code: function _splice(files, length) {
      var spliced = [];
  
      while (files.length) {
          spliced.push(files.splice(0, length));
      }
  
      return spliced;
  }
docs: Divides the given array of files into groups of the given length
  @param {String[]} files
  @param {Number} length
  @returns {Object[]}