update some images to match their 2x version
add UN logo and NY Parks logos; rearrange logos
add retina.js and 2x images
update css for social icons to be retina-ready
convert to using font glyphicon
Merge branch 'widget-cookie-errors' into retina-images

Conflicts:
	public/stylesheets/styles.css
add 2x logo_head
Merge branch 'master' into retina-images
Merge branch 'retina-images'