Improve test coverage: container API
Improve test coverage: container API

Add missing tests for creating, deleting, and updating swift
containers, and getting/setting access information.

Change-Id: I80fd73d7ba5171715d148ce7a1693f94c5b3b40a

openstack/python-openstacksdk,stackforge/python-openstacksdk,dtroyer/python-openstacksdk,dtroyer/python-openstacksdk,openstack-infra/shade,stackforge/python-openstacksdk,openstack-infra/shade,openstack/python-openstacksdk