Add test coverage for security group checking
Add test coverage for security group checking

We had no test coverage for neutron.API._process_security_groups
so this patch adds some basic coverage.

Change-Id: I722b200324d331e72fb74e00788be6adebd4ce3f

openstack/nova,openstack/nova,mahak/nova,mahak/nova,openstack/nova,mahak/nova