improve tox.ini with OS conventions
improve tox.ini with OS conventions

uggla/python-redfish,bcornec/python-redfish,devananda/python-redfish,vmisson/python-redfish,bcornec/python-redfish,devananda/python-redfish,uggla/python-redfish,bcornec/python-redfish,vmisson/python-redfish,uggla/python-redfish