When security_group_api is nova, the update_security_group api raises http
500 error: group rules fails with lazy load exception. Because the rule
infos of the security group will be return in response body, but the rule
attribute hasn't been preloaded.
Closes-Bug: #1244018
(cherry picked from commit b9b55935cb)
Conflicts:
nova/tests/api/openstack/compute/contrib/test_security_groups.py
Change-Id: Ie07879ac22e4add90f75968778bf334915e8349c