link hover, title overlay, quick link banner

quicker link hover transition, smaller quick links banner, cleaner
title overlay now extends left forever with consistent transparency
added -moz & -o to transition mixins, added $color-black-overlay
general <div> styling for post content areas
social media in footer
adjusted padding on sidebars
turned button hover transition back on
add <sup> & <sub> to typography, less bottom margin for <p> tags
removed bottom border on <article>