The os-testr 1.0.0 release had a couple of required config changes due
to it's internal usage of stestr. This commit fixes those by adding a
.stestr.conf (to remove a warning) sets the fixture env variables in
the tox.ini instead of being hidden in .testr.conf and removing the
quotes around posargs to make passing args to ostestr actually work.
Also to keep the expected dev experience stestr is used directly for
places where ostestr was called directly.
Change-Id: Ib0fbcb2e7710a6b8219c56ef2a4462c61ea498a9
