Hide "Milestones" and "Labels" when using an external Issue Tracker and no Wiki
Enhancement: I'd expect GitLab CE to hide the "Milestone" and "Labels" menu entries when using an external Issue Tracker like "Redmine" and having disabled GitLab internal wiki.
I don't see why you would need Milestones and Labels when you have disabled wiki and internal issues.
Otherwise some user roles see the "Milestone" and "Labels" menu entries but can never do anything with it or get empy pages when clicking the links.
