Add demo

If you want to put a demo on github you just have to create a gh-pages branch and it will be accessible at the address.

Here is how you create the branch:
Click on the branch button, search for gh-pages then click create. 
![image](https://cloud.githubusercontent.com/assets/2707767/5522451/09abe41a-89b9-11e4-977c-9c89b9eb4668.png)