Add scripts for integration with devstack

blueprint devstack-integration
Change-Id: I71dc4d7d72f489b8609843e78feba97213ff0f42
Add post_test_hook and pre_test_hook for devstack gate as part of Infra integration

Change-Id: I8b8cef021804db8b856c1785ee547537e017a22b
Merge "Add scripts for integration with devstack"
Adds tempest tests on ReST API get_item

Adds positive tests on get item.
Fix rest client.

Partially implements: bp tempest-rest-api-tests
Change-Id: Iacd3b344db0dbf1f0bdfbdf195902c862d3698db