+ jsDelivr CDN info

[jsDelivr CDN hosting](http://www.jsdelivr.com/#!jquery.midnight) is live.
Seem instructions are best in the README for you, since that is where you put advanced usage.
Push a new [release](https://github.com/Aerolab/midnight.js/releases/), & it should appear on jsDelivr in about 15 minutes.
Merge pull request #14 from tomByrer/gh-pages

+ jsDelivr CDN info