Foreman » Installer

Factor out the foreman-tasks service to a class

Fixes #20819 - Allow turning task cleanup cron on and off

whitelist FreeBSD also in plugins

Clsoes GH-370

refs #4841 - change EL OSes to use 'tfm' SCL prefix

Parameters are supplied on the main foreman class to revert behaviour
for Foreman 1.9 and prior, plus on three plugin classes with
non-standard package names.

Closes GH-348