Foreman » Installer

Only include params class, not top-level class in plugin params

The plugin params classes that rely on foreman_proxy parameters should
only include the foreman_proxy::params class rather than the top-level
foreman_proxy class.

Kafo loads the params classes to determine default parameter values on...

prepare support for more OSes & refactor few tests

refs #8473 - configure salt API in salt.yml

fixes #8875 - support installation/configuration of smart_proxy_salt

Closes GH-135