tox: serial ansible-lint and use ansible.cfg
tox: serial ansible-lint and use ansible.cfg

uses ANSIBLE_CONFIG variable to point to ansible.cfg.example
when tox is running ansible-lint

ansible-lint will be executed not in parallel on all
files (10 threads), instead run in sequence,
should deal with mixed up output

Co-Authored-By: Attila Fazekas <6521b12a893fe78ebc86f655e7566e2d30c5fc4a@redhat.com>
Change-Id: I626929bf4ab89647f3af4460cc4ab54d7654fe91

okolisny/InfraRed,okolisny/InfraRed,redhat-openstack/infrared,okolisny/InfraRed,redhat-openstack/infrared,redhat-openstack/infrared