prepare 2.0 RC4 release

src/Symfony/Component/HttpKernel/Kernel.php

@@ -56,7 +56,7 @@ abstract class Kernel implements KernelInterface
     protected $startTime;
     protected $classes;
 
-    const VERSION = '2.0.0-RC4-DEV';
+    const VERSION = '2.0.0-RC4';
 
     /**
      * Constructor.