##微信支付的坑
###回调
微信请求回调地址的post参数是stream
所以servicestack服务器的route应该写成如下格式
[Route("/callback/wxpay", "Post")]
public class WxPayCallback : IReturn<string>, IRequiresRequestStream
{
/// <summary>
/// The raw Http Request Input Stream
/// </summary>
public Stream RequestStream {get;set;}
}