修复支付结果通知缺失CDATA部分，导致微信重复发送通知

Author: xusheng1987

weixin-java-pay/src/main/java/com/github/binarywang/wxpay/bean/WxPayOrderNotifyResponse.java

@@ -2,7 +2,10 @@
 
 import com.thoughtworks.xstream.XStream;
 import com.thoughtworks.xstream.annotations.XStreamAlias;
+import com.thoughtworks.xstream.annotations.XStreamConverter;
 import com.thoughtworks.xstream.annotations.XStreamOmitField;
+
+import me.chanjar.weixin.common.util.xml.XStreamCDataConverter;
 import me.chanjar.weixin.common.util.xml.XStreamInitializer;
 
 @XStreamAlias("xml")
@@ -13,7 +16,9 @@ public class WxPayOrderNotifyResponse {
   private transient static final String SUCCESS = "SUCCESS";
 
   @XStreamAlias("return_code")
+  @XStreamConverter(value = XStreamCDataConverter.class)
   private String returnCode;
+  @XStreamConverter(value = XStreamCDataConverter.class)
   @XStreamAlias("return_msg")
   private String returnMsg;