修复，支付bug

template/carts/index.js

@@ -144,7 +144,7 @@ Page({
         wx.requestPayment({
           timeStamp: pay.time,
           nonceStr: pay.nonce_str,
-          package: pay.prepay_id,
+          package: 'prepay_id=' + pay.prepay_id,
           signType: pay.sign_type,
           paySign: pay.sign,
           success: function(){//微信支付成功