According to Openstack summit session [1],
stestr is maintained project to which all Openstack projects should migrate.
So we should switch to stestr.
[1] https://etherpad.openstack.org/p/YVR-python-pti
Change-Id: I6c6e1b3873a71d3b069f0c0bc45d9ba9885c2886
This creates the tempest plugin for horizon and duplicates
the existing horizon scenario test in tempest.
Change-Id: I9430b6cefc884ecc105e91ec19a07987aa70ef98