Merge branch '2.8' into 3.4

* 2.8:
  fixed UUID error message id in translation files
  Add several missing translations of the UUID validation message.
  Serbo-Croatian has Serbian plural rule
  [Validator] Add missing UUID validator message translation (hu)
  [Validator] Add missing UUID validator message translation (en)
  add missing translation for uuid validator
  Fix PHPDoc return type
  [MonologBridge] Improve FirePHPHandler
  Fix SVGs not scaling in IE9, IE10, and IE11

Event/GetResponseEvent.php

@@ -29,7 +29,7 @@ class GetResponseEvent extends KernelEvent
     /**
      * Returns the response object.
      *
-     * @return Response
+     * @return Response|null
      */
     public function getResponse()
     {