First version of foreman_ipa module

I think the main benefits would be:

* parameters that affect both foreman_ipa and foreman can be used, e.g. whether SSL is enabled, or httpd is in use
* foreman_ipa is tightly coupled to the implementation of foreman right now (e.g. settings.yaml.erb or httpd), at least that wouldn't be spread over module boundaries

What sort of thing is this going to grow into?