Merge branch '2.7' into 2.8

* 2.7:
  Using FQ name for PHP_VERSION_ID
  [Form] Fix \IntlDateFormatter timezone parameter usage to bypass PHP bug #66323
  Harden the debugging of Twig filters and functions
  bumped Symfony version to 2.7.29
  updated VERSION for 2.7.28
  update CONTRIBUTORS for 2.7.28
  updated CHANGELOG for 2.7.28

Author: fabpot

Loader/AnnotationFileLoader.php

@@ -64,7 +64,7 @@ public function load($file, $type = null)
             $collection->addResource(new FileResource($path));
             $collection->addCollection($this->loader->load($class, $type));
         }
-        if (PHP_VERSION_ID >= 70000) {
+        if (\PHP_VERSION_ID >= 70000) {
             // PHP 7 memory manager will not release after token_get_all(), see https://bugs.php.net/70098
             gc_mem_caches();
         }