Foreman » Installer

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

[plugins:puppetdb] Fix debian package name

As it can be seen in

http://deb.theforeman.org/dists/plugins/nightly/binary-amd64/Packages

the package is ruby-puppetdb-foreman, hyphenated as all other foreman
plugin debian packages.

Fixes GH-256

Add docs to all classes/defines

more quotes around case statements

Enable installation of plugins