Remove npm modules. Tweak sidebar. PHP DOM parser.

- Remove grunt-banner, it was unused
- New `watch.js` file
- Make autoprefixer work
- Make `.toc` keep it's height when it's changed to `position: fixed`
- Modify the images for lazyload with a PHP Simple DOM Parser rather
  than regex
New lazyload. Admin info works.

- Lazyload is now handled by echo.js
- Lazyloaded images have a loader gif
- Lazyloaded images are wrapped in a div
- Lazyloaded images placeholder image now retains its original
  aspect ratio