adding rpnNotify Handler

rpn.go

@@ -155,6 +155,9 @@ func retrieveFormValue(form url.Values, key string) (r string, err error) {
 	}
 	return r, err
 }
+func rpnNotify(w http.ResponseWriter, r *http.Request) {
+
+}
 
 //receive RPN user name and card number
 func rpnNameAndCard(w http.ResponseWriter, r *http.Request) {