update pay order product store rules

go/gopath/src/fohow.com/apps/controllers/pay_controller/pay_exchange_controller.go

@@ -436,7 +436,7 @@ func FindNotEnoughPrd(storeMap map[int64]int64) (bool, string) {
 	}
 	for r_pid, r_nums := range storeMap {
 		product := product_model.GetProductById(r_pid, true)
-		if product.Count < r_nums {
+		if product.Count > int64(0) && product.Count < r_nums {
 			return true, product.Name
 		}
 	}