I was in two minds about that. We've already got enough people who get annoyed with our restrictions on hostnames :P.

In addition, I can only see that we could add the validator in settings.rb using something like `Proc.new {|s| s.name == "foreman_url" ... }` which feels horrible, given you're adding test for something in an STI subclass. I think we'd want to extend the STI inheritance to allow settings to specify their own validators, and thats beyond the scope of this PR, imo.

I'm not against it, however, if there's another solution.