Add/improve live examples to better illustrate functionality

We have an example page that only works after Samizdat is loaded (that is, after at least one visit to the Samizdat site. This is useful, but can be improved upon:

• multiple different examples, showing how Samizdat behaves in different failure modes (depending on what we can simulate just with nginx configs, I guess)
  • 404 Not Found
  • 500 Internal Server Error and/or some other 50x errors
  • blackholing the request (request accepted, no data returned, but connection not terminated, just hanging)
  • response throttled down to a trickle (request accepted, but data returned so slow it's basically useless)
• example of fetch()-less Service Worker to demonstrate possible privacy gain