/**
  * Perform a download
  * 
  * @param  int $id The id of the download
  * @return void
  */
 public function perform($id)
 {
     $download = Download::findOrFail($id);
     $download->access_counter++;
     $download->save();
     $extension = File::extension($download->file);
     $shortName = $download->slug;
     if ($extension) {
         $shortName .= '.' . $extension;
     }
     return Response::download($download->uploadPath(true) . $download->file, $shortName);
 }