Proposal: a sharing-friendly demo page

Basically, the demo page loads a user's card if the "user" parameter is passed, otherwise it defaults to your card (example.png). If the "Show" button is clicked, the page loads user's card and rewrites the URL.

I think this might help your awesome work to spread :-)

![github-card-0-r](https://cloud.githubusercontent.com/assets/941963/3275426/51f14806-f33b-11e3-9038-741ce7d7d410.png)
![github-card-1-r](https://cloud.githubusercontent.com/assets/941963/3275433/5a49aa0c-f33b-11e3-8e98-99c707fd8c40.png)