Fix what account preference is edited where

[tanius]

Due to our SSO account system, some account information is edited at an Edgeryders Communities site (such as edgeryders.eu) and some is edited at the Login Site (communities.edgeryders.eu). This changed somewhat over time, for example profile background and user card background are now editable on Edgeryders Communities sites because syncing that information on login never worked properly.

So several small fixes are required by now, as follows:

1. Prevent editing the profile background and user card background over at communities.edgeryders.eu. As an added benefit, the form to edit things on that site will only be one page then (tab "Account"), so the complete left tabbing bar can be hidden as well.

2. The text in the blue box on /u/[username]/preferences on all Communities sites should be adapted to include "password" and to omit "profile background and user card background". New version, to be adapted with the current username in the link:

   To change your username, email, password, name or profile picture, visit communities.edgeryders.eu.