Update dependencies.
Update normalize.css to v3.0.2.
Update html5shiv, respond.js, jquery and jquery.mousewheel.
README.md: new badge.
Fix validation errors.
Losslessly compress images.

Before: 406 KB (416.526 bytes)
After:  393 KB (403.234 bytes)
8-bit thumbnails.

Before: 189 KB (193.931 bytes)
After:  52,6 KB (53.897 bytes)