Online playground to generate & export graph

[nicoespeon]

I love that Term Sheets provides an online playground on their website, so you can actually use the tool without installing anything. 👐

I'd like to do the same on Gitgraph.js website, once v2 is out.

People should be able to:

• export the generated SVG (from gitgraph-react)
• export an image

[rjmunro]

You can use http://jsfiddle.net/fracz/q76vj8ow/