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