Support manage_httpd to allow Pulp in a standalone setup (followup)

[laugmanuel]

Follow up to #312

This PR enables Pulp to exist as a standalone system and therefore enables split deployments.

The default behaviour does not change in any way. It it explicitly required to set a least manage_httpd to true.

Note: The original PR is #312. Because the source branch was missing, I needed to open a new PR with an existing branch I can push to.

[ekohl]

We can bikeshed about names (manage_httpd doesn't seem too clear since Apache is managed either way) but since we plan on Removing Pulp 2 after Foreman 2.2 I don't mind either way. This particular class is not typically used by most users since the installer doesn't expose it.

Let me know if you want me to merge this as is or if you want to rename manage_httpd.

[laugmanuel]

@ekohl sure we can rename the parameter. What do you think about manage_httpd_standalone or something like that? This would also indicate the change in behaviour.

[ekohl]

You could say that pulp is standalone, but it's more about a vhost than httpd (yes, badly named in puppet-pulp) so Boolean $manage_vhost_standalone? However, I don't really know what it would do if you say false so I was thinking in the direction of Enum['foreman', 'pulp'] $vhost. It's complicated.

For now I'm thinking the easiest would be Boolean $manage_vhost_standalone and document that it's part of the Foreman vhost when it's not standalone in the parameter documentation. What do you think?

[laugmanuel]

Sounds good to me. I changed the name of the variable and improved the parameter documentation accordingly.

[ekohl]

(I'll let the tests continue, but the code looks good to merge).