Fix test_http test case.
Fix test_http test case.

Fix and complete test cases for http.py client classes.

Change-Id: Iaffb249dd7393b334e94149a2da3e8310af3295a

openstack/tempest,masayukig/tempest,cisco-openstack/tempest,masayukig/tempest,cisco-openstack/tempest,openstack/tempest