Fixed Admin Order Updates

With the "&& ($this->request->server['REQUEST_METHOD'] != 'POST')" still in the changed line, updating an order from the admin panel caused a long list of errors stating $order_info wasn't defined.

Besides I don't see the need to check the GET variable and the request method, if the get is set, then we obviously didn't use POST. and if it was a POST, the GET will not be set, if I am wrong, please let me know how, and show me a better way to do this.