Use specific key to sort list of dicts
Use specific key to sort list of dicts

In python3, sorted() list of dicts will report error:
b'TypeError: unorderable types: dict() < dict()'
This patch fix the problem.

Partially-Implements: blueprint magnum-python3

Change-Id: I5db635712f3128b60d05360ac26a008f49a21850

openstack/magnum,openstack/magnum,ArchiFleKs/magnum,jay-lau/magnum,ArchiFleKs/magnum