Tweak `setup_site_url` to include https, and uniformity

Because SSL certs have feelings too, man. It's not the prettiest thing visually (paging @philwareham), but it will avoid misconceptions about Textpattern being an `http`-only thing.

Also, switch the first instance of `Textpattern` to `Textpattern CMS` for branding. It's indented by 110% in the CSS so doesn't appear, but that's intentional - right?