New article: Introduction to Shadow DOM

Post an introductory article along with [DevBytes video](https://www.youtube.com/watch?v=Is4FZxKGqqk).
Remove trailing spaces

![screen shot 2014-10-28 at 5 26 17 am](https://cloud.githubusercontent.com/assets/398893/4808593/97b37788-5ea2-11e4-8bbd-f35bccb4f71c.png)