Merge branch '3.4' into 4.2

* 3.4:
  fix translating file validation error message
  [Validator] Add missing Hungarian translations
  [3.4] [Validator] Add missing french validation translations.
  [Validator] Only traverse arrays that are cascaded into
  Handle case where no translations were found
  [Validator] Translate unique collection message to Hungarian
  fix tests
  Run test in separate process
  Use a class name that does not actually exist
  fix horizontal spacing of inlined Bootstrap forms
  [Translator] Warm up the translations cache in dev
  turn failed file uploads into form errors

Tests/ErrorHandlerTest.php

@@ -481,7 +481,7 @@ public function testHandleFatalError()
 
     public function testHandleErrorException()
     {
-        $exception = new \Error("Class 'Foo' not found");
+        $exception = new \Error("Class 'IReallyReallyDoNotExistAnywhereInTheRepositoryISwear' not found");
 
         $handler = new ErrorHandler();
         $handler->setExceptionHandler(function () use (&$args) {
@@ -491,7 +491,7 @@ public function testHandleErrorException()
         $handler->handleException($exception);
 
         $this->assertInstanceOf('Symfony\Component\Debug\Exception\ClassNotFoundException', $args[0]);
-        $this->assertStringStartsWith("Attempted to load class \"Foo\" from the global namespace.\nDid you forget a \"use\" statement", $args[0]->getMessage());
+        $this->assertStringStartsWith("Attempted to load class \"IReallyReallyDoNotExistAnywhereInTheRepositoryISwear\" from the global namespace.\nDid you forget a \"use\" statement", $args[0]->getMessage());
     }
 
     /**