库存不足提示字样更新. code review by zhaobiao

@@ -66,7 +66,7 @@ $('.freebie').on('touchend', function() {
 
 $('.btn-balance').on('touchend', function() {
     if ($('.low-stocks').length > 0) {
-        tip.show('请先删除库存不足商品');
+        tip.show('库存不足无法结算');
         return false;
     }