Add script for unit test coverage job

[Sharat Sharma]

Add script and coverage config file that will allow to run
non voting coverage job which will detect any changes in the code coverage
for each commit on review.

[Sharat Sharma (sharat-sharma)]

https://review.openstack.org/#/c/417902/
for mistralclient

[Sharat Sharma (sharat-sharma)]

https://review.openstack.org/#/c/417881/1
for mistral

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.opendev.org/700832

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/700832
Committed: https://git.openstack.org/cgit/openstack/python-mistralclient/commit/?id=f5b15b6f6b6cbef11db8e0fe4f50b52dda1efb8b
Submitter: Zuul
Branch: master

commit f5b15b6f6b6cbef11db8e0fe4f50b52dda1efb8b
Author: Sharat Sharma <email address hidden>
Date: Fri Jan 6 22:11:59 2017 +0530

    Add script for unit test coverage job

    This patch will allow to run a non voting coverage job
    which will detect any changes in the code coverage for
    each commit on review.

    Change-Id: Ie2bb1b23bb49f0f3b1a149b8e086c2a943f77508
    Closes-Bug: 1655016

[OpenStack Infra (hudson-openstack)]

This issue was fixed in the openstack/python-mistralclient 4.0.0 release.