Default deleteFileAfterSend() to true

This should default to true when called since there is only one option.

Author: nowendwell

src/Symfony/Component/HttpFoundation/BinaryFileResponse.php

@@ -350,7 +350,7 @@ public static function trustXSendfileTypeHeader()
      *
      * @return $this
      */
-    public function deleteFileAfterSend($shouldDelete)
+    public function deleteFileAfterSend($shouldDelete = true)
     {
         $this->deleteFileAfterSend = $shouldDelete;