Better headers for CGI enviroments

git-svn-id: http://svn.automattic.com/wordpress/trunk@2623 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-admin/admin.php

@@ -7,10 +7,7 @@ else
 require_once(ABSPATH . 'wp-admin/admin-functions.php');
 auth_redirect();
 
-header('Expires: Wed, 11 Jan 1984 05:00:00 GMT');
-header('Last-Modified: ' . gmdate('D, d M Y H:i:s') . ' GMT');
-header('Cache-Control: no-cache, must-revalidate, max-age=0');
-header('Pragma: no-cache');
+nocache_headers();
 
 update_category_cache();