Updates build process.
Updates download.
Updates download.
Losslessly compress PNG files.
cosmetics
Update README.md.

* specify the code language used
* Github uses https
* Modernizr is licensed under MIT license
Update package.json.

* add bugs property
* specify minimum node.js version
Update markdown-js to 0.5.0+.
Update HTML5 Boilerplate to v4.3.0.