Domain Actions Test Case-V3

This submission adds one testcase test_create_update_delete_domian
to "test_domains.py" so as to verify create, update, get,
actions on domains

Change-Id: I10d449bb07d20d681098e95295ca081e8f9172ec
Implements: blueprint keystone-v3-domain-api-test
Merge "Domain Actions Test Case-V3"