Updated openstack/openstack
Project: openstack/tempest  ec93c1ea1aa16aeb89cec701b9f1904106357441
null
Add list user groups api to identity v3

Identity v3 lack of list user groups, so I do the addition.
To test the addition, I add a test :
- test_list_user_groups

Change-Id: I5924b7c6c9dfe61cb4089ad9a09d2da0c0bd18c4