Merge branch '3.1' into 3.2

* 3.1:
  [TwigBundle] fixed usage when Templating is not installed
  [Validator] Check cascasdedGroups for being countable
  [Cache] Add changelog
  [Filesystem] Check that the directory is writable after created it in dumpFile()
  [HttpFoundation] Improved set cookie header tests
  [Serializer] int is valid when float is expected when deserializing JSON
  [Console] increased code coverage of Output classes
  Added missing headers in fixture files
  [Profiler][VarDumper] Fix minor color issue & duplicated selector

Author: fabpot

Tests/Fixtures/Controller/BasicTypesController.php

@@ -1,5 +1,14 @@
 <?php
 
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
 namespace Symfony\Component\HttpKernel\Tests\Fixtures\Controller;
 
 class BasicTypesController

Tests/Fixtures/Controller/ExtendingRequest.php

@@ -1,5 +1,14 @@
 <?php
 
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
 namespace Symfony\Component\HttpKernel\Tests\Fixtures\Controller;
 
 use Symfony\Component\HttpFoundation\Request;

Tests/Fixtures/Controller/VariadicController.php

@@ -1,5 +1,14 @@
 <?php
 
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
 namespace Symfony\Component\HttpKernel\Tests\Fixtures\Controller;
 
 class VariadicController