Merge branch '2.4' into 2.5

* 2.4:
  [HttpKernel] added an analyze of environment parameters for built-in server.
  change command to which available under most unix systems
  add way to test command under windows
  fix shell command injection
  [Form] allowed CallbackTransformer to use callable
  [Process] Added process synchronization to the incremental output tests

Author: fabpot

Resources/config/router_dev.php

@@ -25,6 +25,7 @@
     return false;
 }
 
+$_SERVER = array_merge($_SERVER, $_ENV);
 $_SERVER['SCRIPT_FILENAME'] = $_SERVER['DOCUMENT_ROOT'].DIRECTORY_SEPARATOR.'app_dev.php';
 
 require 'app_dev.php';

Resources/config/router_prod.php

@@ -25,6 +25,7 @@
     return false;
 }
 
+$_SERVER = array_merge($_SERVER, $_ENV);
 $_SERVER['SCRIPT_FILENAME'] = $_SERVER['DOCUMENT_ROOT'].DIRECTORY_SEPARATOR.'app.php';
 
 require 'app.php';