Update dependencies.
Update libraries.

* normalize.css to v3.0.2.
* html5shiv v3.7.2
* respond.js v1.4.2
* jquery v1.11.1
* jquery.mousewheel v3.1.12
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)