Merge branch '2.7' into 2.8

* 2.7:
  fixed undefined variable
  Fixed the phpDoc of UserInterface
  fixed APCu dep version
  make apc class loader testable against apcu without apc bc layer
  Added support for the `0.0.0.0/0` trusted proxy
  [DoctrineBridge][Validator] >= 2.3 Pass association instead of ID as argument
  added missing constant
  Added 451 status code
  Remove unnecessary code
  Allow absolute URLs to be displayed in the debug toolbar
  [ClassLoader] Use symfony/polyfill-apcu
  [HttpKernel] Lookup the response even if the lock was released after 2 seconds

Author: fabpot

DependencyInjection/Configuration.php

@@ -139,6 +139,10 @@ public function getConfigTreeBuilder()
                                 }
 
                                 if (false !== strpos($v, '/')) {
+                                    if ('0.0.0.0/0' === $v) {
+                                        return false;
+                                    }
+
                                     list($v, $mask) = explode('/', $v, 2);
 
                                     if (strcmp($mask, (int) $mask) || $mask < 1 || $mask > (false !== strpos($v, ':') ? 128 : 32)) {

Tests/DependencyInjection/ConfigurationTest.php

@@ -66,6 +66,7 @@ public function getTestValidTrustedProxiesData()
             array(array(), array()),
             array(array('10.0.0.0/8'), array('10.0.0.0/8')),
             array(array('::ffff:0:0/96'), array('::ffff:0:0/96')),
+            array(array('0.0.0.0/0'), array('0.0.0.0/0')),
         );
     }