Options to format SendForm item list

[fcsobel]

Add SendForm options itemFormat & indexStart to allow list formatting.

Ex: Can be used to format POST for simple asp.net mvc model binding:

        simpleCart({
            checkout: {
                type: "SendForm",
                url: "/checkout",
                method: "POST",
                itemFormat: 'items[{index}].{name}',
                indexStart: 0
            }
        });

Results in post that will bind to list of items:
http://haacked.com/archive/2008/10/23/model-binding-to-a-list.aspx/

  items[0].name
  items[0].quantity
  items[0].price
  items[0].options
  items[1].name
  items[1].quantity
  items[1].price
  items[1].options
  ...etc

Example c# checkout model

    public class CheckoutModel
    {
        public string Currency { get; set; }
        public decimal Tax { get; set; }
        public decimal TaxRate { get; set; }
        public int ItemCount { get; set; }
        public List<CartItem> Items { get; set; }
    }

    public class CartItem
    {   
        public string Name { get; set; }
        public int Quantity { get; set; }
        public decimal Price { get; set; }
        public string Options { get; set; }
    }