Integration tests cleanup

This patch does a cleanup and fixes some nits found by reviewers
in the original patches [1], some of them are:

- import json instead of jsonutils
- use six.moves.http_client
- put common logic on clients superclass
- use "fails" to indicate negative cases
- stronger comparison in update tests

[1] https://review.openstack.org/#/q/topic:federation_integration_tests

Change-Id: I216fc5d4758e7b09d167d9d26271ddd149c66816
7 files changed
tree: 89735cb7021ed7e644f27719aabe8784d81af4b0
  1. keystone_tempest_plugin/