Replace the link + logo for the Marseille university because it's outdated + wrong!

Viktor had mentioned that many months ago but never replied to repeated inquiries. Now I did the check…

Turns out that Viktor's university underwent a sweeping change of branding and moved their website to a new URL.

We should replace the logo + URL on the welcome/login page. Maybe also in the documentation somewhere – don't know whether it's used there too.

The currently used URL runs against a static "redirect" and it might be closed.

The new URL (in English) is: http://edu.univ-amu.fr/en

This change ensures a professional impression of the product and shows due respect to one of our largest sponsors.