Adds new logo sprites

@2x for 'retina' displays and @1x for 'normal' displays. My math was off - originall I meant to be using a 1.5x sprite, but was using 2.5x. Anyhoo, either way, background-size isn't playing nice with IE8 and I really don't want to add another js shim so I'm going to update the logo CSS to point to the naturally-sized image.
Renames log sprites and removes old log image
Adds 'retina' support

Also, as a side effect, fixes the background-size issues IE8 has.
Removes outdated .about styling
Adds top margin to social links list
Reverts file to linking to min.css
Adds minified CSS, featuring code form previous commits