code review by hf: fixes bug to add shopping to cart

@@ -457,7 +457,7 @@ class IndexController extends AbstractAction
 
             // 设置加入购物车凭证到客户端浏览器
             if (!$shoppingKey && isset($result['data']['shopping_key'])) {
-                $this->setCookie('_spk', $result['data']['shopping_key']);
+                $this->setCookie('_Spk', $result['data']['shopping_key']);
             }
         }