oslo project provide jsonutils, and karborclient use it in many place[1], this PS to update the remained json module to oslo jsonutils for consistency. [1]: https://github.com/openstack/python-karborclient/search?utf8=%E2%9C%93&q=jsonutils&type= Change-Id: I8c2c0383eac12a5562f205640d6c8c7d062266b1