Updated openstack/openstack
Project: openstack/tempest  8ef26d4b56380c39ee2885bea487f7953f59d252

Fix doc for usage of python clients in scenario tests

Scenario tests has been migrated from official python clients to
Tempest clients.
Documents for the same needs to be fixed.

This patch fix the README & HACKING file for above changes.

This patch also extends hacking rule of not import python clients
for scenario tests too.

Change-Id: Ieb19a2c0b09f00fb3d4f6c7c73541275a4cf24ae