Revert "FIX: Download of files named "true" or "false" impossible"

This reverts commit d2d71c8797.
which was accidentally commited

apps/files/ajax/download.php

@@ -34,9 +34,8 @@ $files = $_GET["files"];
 $dir = $_GET["dir"];
 
 $files_list = json_decode($files);
-
 // in case we get only a single file
-if ($files_list === NULL || $files_list === true || $files_list === false) {
+if ($files_list === NULL ) {
 	$files_list = array($files);
 }