Modify "Sign In" text depending on site status

An initial step on the journey.

A quick look at some of the thoughts in #14 _Let's be clear who owns each wiki_

Using the CSS Persona Sign In so message can be varied depending on if the site is owned or not.

Also if the site is owned display the name of the site owner, for now it will just be the name before the '@' in the email address.

Still need to look at logging in a somebody other than the owner...