First version of foreman_ipa module

Enrolment sounds like a strange thing to do in Puppet, but ok.  That might be better in another module that we can use, as it's not Foreman-specific.

Sounds like the best thing to do is split the generic things into another IPA-specific module (like @purpleidea's if applicable) and keep the Foreman-specific configuration in "foreman", rather than trying to create a niche module for this one purpose.  This will make it easier to maintain and reuse the code.