append(source, data, callback) {
    this.engine.entry(source, data, callback);
  }
@param  {(Buffer|Stream)} source
@param  {ZipEntryData} data
@param  {String} data.name Sets the entry name including internal path.
@param  {(String|Date)} [data.date=NOW()] Sets the entry date.
@param  {Number} [data.mode=D:0755/F:0644] Sets the entry permissions.
@param  {String} [data.prefix] Sets a path prefix for the entry name. Useful
when working with methods like `directory` or `glob`.
@param  {fs.Stats} [data.stats] Sets the fs stat data for this entry allowing
for reduction of fs stat calls when stat data is already known.
@param  {Boolean} [data.store=ZipOptions.store] Sets the compression method to STORE.
@param  {Function} callback
@return void