Create salt and deploy user/group in addition to the sudo capabilites.
This changes does NOT populate those groups. That will be done in the
forest account provisionning follow-up change.
The new Salt directory structure is given to the salt-wrapper configuration.
We currently let the woodscloud test values used for salt-wrapper development,
but we aren't sure it's still required. If so, it's to move to /opt/salt too.
Fixes T1272.
An init state has been prepared, to allow to only include roles/saltmaster.
Ref T1273