updated CHANGELOG for 2.0.23
update CONTRIBUTORS for 2.0.23
updated VERSION for 2.0.23
Merge branch '2.0' into 2.1

* 2.0:
  updated VERSION for 2.0.23
  update CONTRIBUTORS for 2.0.23
  updated CHANGELOG for 2.0.23

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