Styleguide improvements

Spring cleaning. :sun_with_face: 

### Styleguide Changes:

 - Show version from `package.json` on style guide.
 - Use "header" pattern on the style guide. New KSS block styling.
 - KSS block descriptions can now contain Markdown.
 - KSS block code samples now have syntax highlighting.
 - Some better organization for style guide assets and views.

### Pattern Changes:
 - Header pattern now uses CSS3 gradients for both "hero" and "basic" styles. (@c7b2e27)
 - Subheadings `h3, h4` are now purple.
 - Updated appearance of `img.bordered` and `figure` patterns.
 - Removed `.page` and `.breadcrumbs` patterns.