Auto-save (and auto-load) analytics data.
Mention that contributors should modify `try.html`.

Fixes #131.
Point to badges/shields
Consolidate example image URL and JS code

Before they had diverged and the link generator lacked the `img.` subdomain.
Deploy includes uploading the new website.
innerText → textContent

innerText is not supported in Firefox (and probably others).
textContent is supported everywhere since IE9.

Related to issue #133.