Add ostestr tox jobs

This commit adds tox jobs to run tempest with ostestr instead of the
pretty_tox*.sh wrappers. ostestr provides essentially the same
functionality except it exposes slightly more rich selection logic
and additional debugging options. However, since the cli isn't
backwards compatible with pretty_tox we can't simply remove the old
tox jobs.

Change-Id: I347438b1d561af7e05fdce895e2e3e51d2b38b0c
1 file changed