First version of foreman_ipa module

@domcleal The biggest reason to do enrollment in Puppet is it's not easy to do the right thing for sudoers, and the installer won't do it until 4.x.  The shell script to do it is ugly.

  https://github.com/stbenjam/puppet-ipaclient/blob/master/manifests/sudoers.pp

Enrollment built-in to the installer would be nice for testing purposes, too.