Add Product to Shopping Cart using Ajax

使用Ajax将产品添加到购物车，参考案例如下：

• http://excellencemagentoblog.com/blog/2011/10/04/magento-add-product-to-cart-ajax/
• http://excellencemagentoblog.com/blog/2011/10/23/ajax-based-product-add-to-cart-from-category-page/
• http://excellencemagentoblog.com/blog/2011/10/27/magento-ajax-based-add-product-to-wishlist-and-compare-products/