Require upgrade.php when running the "upgrade" command

Fixes the "Call to undefined function wp_upgrade() in
/usr/bin/noblogs:251" error.

bin/noblogs.in

@@ -239,7 +239,7 @@ function do_check_upgrade($args) {
 
 // 'upgrade': Upgrade a blog.
 function do_upgrade($args) {
-  //include(NOBLOGS_ROOT . "/wp-admin/includes/upgrade.php");
+  require_once(NOBLOGS_ROOT . "/wp-admin/includes/upgrade.php");
 
   foreach ($args as $arg) {
     $blog = noblogs_get_blog($arg);