1. oslo project provide jsonutils, and barbican use it in many place[1],
this PS to update the remained json moudule to oslo jsonutils for
consistency.
2. update the primary jsonutils to use alias json
[1]: https://github.com/openstack/barbican/search?utf8=%E2%9C%93&q=jsonutils&type=
Change-Id: I958a711db17bb1aa86fc4cd23c00cec185b84ab2