Improved iac-management flexibility

[spresser-hlrs]

Currently the iac-management modules are tied to specific distributions and versions. For example, some modules will not run except on Ubuntu 16.04. This sharply limits the applicability of the modules.
The modules should be generalized to more (and especially more recent) operating systems and OS versions
This task may be easier if combined with “Improved iac-management testing” (#20).

Please let me know if this needs more detail and/or discussion at the technical meeting.