Merge branch '2.8' into 3.2

* 2.8:
  Don't display the Symfony debug toolbar when printing the page
  allow to configure custom formats in XML configs
  require the XML PHP extension
  Fixed absolute url generation for query strings and hash urls
  bumped Symfony version to 2.8.25
  updated VERSION for 2.8.24
  updated CHANGELOG for 2.8.24
  bumped Symfony version to 2.7.32
  [Filesystem] Dont copy perms when origin is remote
  updated VERSION for 2.7.31
  update CONTRIBUTORS for 2.7.31
  updated CHANGELOG for 2.7.31

Author: nicolas-grekas

composer.json

@@ -17,6 +17,7 @@
     ],
     "require": {
         "php": ">=5.5.9",
+        "ext-xml": "*",
         "symfony/http-kernel": "~2.8|~3.0",
         "symfony/twig-bridge": "~2.8|~3.0",
         "symfony/var-dumper": "~2.8|~3.0"