Tweak `setup_site_url` to include https, and uniformity

Because SSL certs have feelings, man.

Also, switch the first instance of `Textpattern` to `Textpattern CMS`
for branding.
Switch URLs to RFC2606

https://tools.ietf.org/html/rfc2606

At least one was linking to porn. Oops. The others were domain squatter
websites.
Uniformity: `admin side` to `admin-side`
Merge pull request #446 from petecooper/master

Presentational tidying and tweaks