[#31516] Use the Social JLayouts from #5252 in com_content as an example

Uses #5252 to create social icons in com_content (as part of http://joomlacode.org/gf/project/joomla/tracker/?action=TrackerItemEdit&tracker_item_id=31516)

This PR is NOT intended to be the one merged - but is the one that allows easy testing of #5252.

This PR is the same as https://github.com/joomla/joomla-cms/pull/2173 except against staging instead of master