"View Page" button should use site URL when available

[axis80]

Currently when you are in the editor and click the "View Page" button to preview a page, it uses a URL path that is relative to the root of the main CMS installation.

It would be preferable if this would use the URL defined in the site settings, when that is available. The main reason is that editors will sometimes copy/paste the page URLs and publish them elsewhere, which exposes the URL of the CMS installation to the public.