Basic icon overlays, eradicate all uses of `!important`.

This adds basic icon overlays that can appear before or after a font-awesome
`span`; use `.k-icon-overlay` and optionally `.k-icon-overlay-before` or
`.k-icon-overlay-after` (default is after).

Add rule weight using `body` and/or `html` instead of using `!important`; the
latter means something subtly different.
Use a non-blurred font border on overlays rather than a blurred shadow.
Working icon overlays, with "nudge" classes for oddly-shaped icons.
Add mockup for reverse-video `k-button` components.
Change `k-` namespace to `mm-` by request.

The `k` stood for Ketamine, not that older product name that shall not be
mentioned. It's a programming language, clearly.
Merge pull request #2 from browndav/master

Merge #2 from browndav/kujua-visual