This change updates the tox.ini file to call stestr
directly instead of going through ostestr.
For more background you can read the ML posting:
So now you won't need `--n` to run single tests, and you
can also supply regex directly without even the `--`.
`tox -epy27 $regex`
Some of available checks are disabled by default,
like:[H106] Don’t put vim configuration in source
files;[H203] Use assertIs(Not)None to check for None;
[H904] Delay string interpolations at logging calls
Keystone session can be used directly in user function to access
Include openstack clients in python requirements as well.
Add a python function example.
Implements: blueprint qinling-openstack-clients