Add Grunt support.

Combine and minify CSS and JS files.

Also, include the version from package.json in the CSS and JS filenames and increase the expires headers for those files to 1 year.
index.html: remove unused ID.
Add plugins.js from html5 boilerplate.
Add Ubuntu regural font generated with FontSquirrel.
Specify X-UA-Compatible.

Though the visitors using IE should be only few, it's a good practice forcing the last IE version.
README.md: Add dependency status badge.