No checks of ajax requests

Not all servers detect HTTP_X_REQUESTED_WITH header.
And now it is possible to load excel files.

~dev_rating/application/classes/Controller/Handler.php

@@ -12,9 +12,6 @@ class Controller_Handler extends Controller
     protected $user;
 
     public function before() {
-        if (!$this->request->is_ajax())
-            throw new HTTP_Exception_404();
-
         $this->user = User::instance();
         $this->post = Validation::factory(Arr::map('trim', $_POST));
         $this->get = Validation::factory(Arr::map('trim', $_GET));