Refstack-client should use stestr for tempest testing

[Zhenyu Zheng]

Tempest has changed to use stestr instead of testr and testrepository starting from 18.0.0,and the testr.conf was removed:
https://review.openstack.org/#/c/504345/

refstack-client will not able to run for tempest 18.0.0 as some commands need the testr.conf in the path:

root@defcore:/home/defcore/refstack-client/refstack_client# /home/defcore/refstack-client/.tempest/tools/with_venv.sh testr list-tests
No .testr.conf config file

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/562956

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/562956
Committed: https://git.openstack.org/cgit/openstack/refstack-client/commit/?id=74b6ac1c3ffccf60e16205de3bea501f8c5944f4
Submitter: Zuul
Branch: master

commit 74b6ac1c3ffccf60e16205de3bea501f8c5944f4
Author: Chandan Kumar <email address hidden>
Date: Thu Aug 16 17:25:51 2018 +0530

    Refstack-client should use stestr for tempest testing

    Tempest has changed to use stestr instead of testr and testrepository
    starting from 18.0.0,and the testr.conf was removed:
    https://review.openstack.org/#/c/504345/

    refstack-client will not able to run for tempest 18.0.0 as some commands
    need the testr.conf in the path:

    root@defcore:/home/defcore/refstack-client/refstack_client#
    /home/defcore/refstack-client/.tempest/tools/with_venv.sh testr
    list-tests
    No .testr.conf config file

    Tempest Commit SHA: 8316f962c52b01edc5be466b18e54904e2a1248a pointing
    to tempest 19.0.0

    Install tempest from master

    Updated Guidelines to match 2018.02

    Change-Id: Ic796cc7ad48037e64a4437d4834051c7fa7cbda1
    Closes-Bug: #1765609