Merge branch '2.7' into 2.8

* 2.7:
  Remove usage of __CLASS__ outside of a class
  [HttpKernel] Fix variable conflicting name
  [Process] Fix double-fread() when reading unix pipes
  [Process] Fix AbstractPipes::write() for a situation seen on HHVM (at least)
  [Validator] Fix dockblock typehint in XmlFileLoader
  bumped Symfony version to 2.7.17
  updated VERSION for 2.7.16
  update CONTRIBUTORS for 2.7.16
  updated CHANGELOG for 2.7.16

Conflicts:
	src/Symfony/Component/HttpKernel/Kernel.php

Author: nicolas-grekas

Mapping/Loader/XmlFileLoader.php

@@ -182,13 +182,7 @@ protected function parseFile($path)
         return simplexml_import_dom($dom);
     }
 
-    /**
-     * Loads the validation metadata from the given XML class description.
-     *
-     * @param ClassMetadata $metadata         The metadata to load
-     * @param array         $classDescription The XML class description
-     */
-    private function loadClassMetadataFromXml(ClassMetadata $metadata, $classDescription)
+    private function loadClassMetadataFromXml(ClassMetadata $metadata, \SimpleXMLElement $classDescription)
     {
         if (count($classDescription->{'group-sequence-provider'}) > 0) {
             $metadata->setGroupSequenceProvider(true);