Admin interface: settings improvements

Squashed commit of the following:

commit 703127f7cee5a0a3a3a68df12b61d41e4143c896
Author: Michał Podlecki <m.podlecki@op.pl>
Date:   Thu Feb 13 15:06:51 2014 +0100

    Squashed commits:

    show settings page as index view

    add edit links on settings page

    settings are editable via their edit pages

    edit media set on its details view

    fix broken feature tests