Support non-mirror deployments without Foreman

[ekohl]

In 5718a34 initial support was added for Pulpcore as a mirror. There is also some code to allow running a Pulpcore as non-mirror without Foreman, but right now it's not possible to configure this:

puppet-foreman_proxy_content/manifests/init.pp

Lines 150 to 151 in edc7b5f

	# TODO: doesn't allow deploying a Pulp non-mirror without Foreman
	$shared_with_foreman_vhost = !$pulpcore_mirror

The idea is that it could end up deploying just a content proxy without Foreman but still is a non-mirror. Essentially you could end up with foreman.example.com (with Katello, without Pulp) and pulp.example.com (primary content storage). Then you could also have mirror.location.example.com which would be a local mirror.