Merged Piotr's pf_retina_assets and fixed a feature test

Squashed commit of the following:

commit b81a06cc236082abe2c67a2647832253b3c34576
Author: Thomas Schank <DrTom@schank.ch>
Date:   Thu Nov 21 12:06:47 2013 +0100

    Fix feature test

commit 5d12ba8e93c958e3203ea6319421a30c3636385e
Author: Thomas Schank <DrTom@schank.ch>
Date:   Thu Nov 21 11:49:14 2013 +0100

    Merged Piotr's pf_retina_assets

    Squashed commit of the following:

    commit ef1330de2a3a69383f54ad13eded8773572337e9
    Author: Thomas Schank <DrTom@schank.ch>
    Date:   Tue Nov 19 14:31:42 2013 +0100

        Squashmerged (again) pf_retina_assets on to of next

        Conflicts:
        	app/views/permissions/edit.html.haml
        	app/views/styleguide/3 Buttons & Links/_buttons_and_links.html
        	app/views/styleguide/6 Components/_components.html
        	app/views/styleguide/7 Combos/_combos.html