Extension samples conventions

[dotproto]

@samthor's comment on PR #580 got me thinking: what conventions should we adoption for extension samples?

A practice I've adopted in a couple examples is to open a demo page immediately after installing the extension. This makes it super easy to start experimenting with the demo and poking around in DevTools. I think this is a solid pattern we should use across the demos.

I also think the use of awsm.js in the Action API demo did a lot to making the demo more inviting and to feel good to use.

Should we open a demo page on action click?

Should samples provide options pages? If so, what would they do?

I'd like to publish API samples to CWS and link them from the appropriate API reference pages in order to make it easy to find and experiment with the extensions.