Synced jsonutils from oslo-incubator

The sync includes change that drastically enhances performance on Python
2.6 with fresh simplejson library installed.

The latest commit in oslo-incubator:
- 732bdb6297eb9de81667f7713ebcb1ccc2ee45a7

Change-Id: Ib3dc0b713ed90396919feba018772243b3b9c90f
Closes-Bug: 1314129
Use oslo.config for heat-keystone-setup-domain

Previously used environment variables exclusively.

Change-Id: If4b4266ce66212d7ae2579e7da6d3bae779ad04a
Merge "Synced jsonutils from oslo-incubator"