Updating the CSS to match h5bp Version 4.
…d. It's now too difficult to make the selection a separate mixin because it's buried in the base styles mixin. Adding in a chromeframe file that is never called with a warning in case people were including that file directly. Chromeframe has moved to the _main.scss file to more closely match the updated layout of Boilerplate version 4.0.
Updated image-replacement mixin
Updated to h5bp v2 selection color
Adding missing mixin to readme
update scss to 3.0 and add test
…tuff since that's the one thing that boilerplate does that is super annoying.