Demo page

Fixes #3.

It also includes the changes in #1, diffs will go away when we merge #1.

![demo1](https://cloud.githubusercontent.com/assets/643127/3298408/4c1164a2-f601-11e3-8051-0dfbbca1965b.png)
![demo2](https://cloud.githubusercontent.com/assets/643127/3298409/4c11794c-f601-11e3-865e-5a42bdf55fd4.png)


cc @skidding @NiGhTTraX 


Seeing something like: `Changed node: <div>testing something by hand</div>` might be more suggestive. It might be big, but you can always trim if from css with text-overflow ellipsis or something like that...