This commit is a follow-up of "switch to using stestr"
which was merged already [1].
After switch to using stestr, testrepository and .testr.conf
are unnecessary and should be removed.
This patch also switch from "testr" to "stestr" for coverage jobs.
[1] https://review.openstack.org/575430
Change-Id: Ide998f902197ff24e28e998daa8defda090fab3f
Moved what were called unit tests to the functional directory as there is
more work to be done to make them self supporting.
Added sphinx to the test-requirements along with testr deps.
Adjusted the tox.ini to suit.
Added doc source tree with the minimal set of files to allow sphinx
success.
Change-Id: Ic64c2ccd01778bb0d1142d12ca43b2346bdc7aa7