Samba

This pull request is not fully tested. But placed here so that we have something to  talk about.

 I tried a lot of things before I discovered the I can create an optional role, by defining both a tag, and a "when: variable is defined" clause.  I think all roles should have that, and then we could use a GUI  to populate a global vars file.  (for initial testing, we'd use a vars file with all roles defined).