- Added an overlay to reject IE8 and below with an IE conditional
- Slimmed down markup and css for IE rejection <div>
Simple mustard cut based on Filament Group's enhance.js

- Inline enhance.js in <head> to async load css and js
- IE8 and lower is cut off by detecting getElementsByClassName
- overlay.js needs domready to work even on qualified IE versions (9+),
  so ready.js is conditionally required with parts from
  github.com/stowball/Layout-Engine
- Exclude js modules/partials from jekyll --watch
Build system update:

- Added separate task to uglify and inline enhance.js
- Clean sourcemaps from deploy/