public function newAction()
 {
     $param['category'] = $this->_getParam('category');
     $app = Model_Category::find($param['category']);
     if ($app) {
         throw new Exception("Category '" . $param['category'] . "' already exist.");
     }
     $c = new Model_Category();
     $c->newCategory($param);
     echo json_encode(array('success' => true));
 }