Fixes #176

Removes most of the examples and replaces them with one TCK-verified, strict-adhering to the spec, documented asynchronous `AsyncIterablePublisher`.
This should address #176 for now, and more examples, preferably an `AsyncSubscriber` would be great.

@reactive-streams/contributors Yay or nay? Weigh in here before the 19th (this is example code so does not affect spec or interfaces)
Sanity check: btw, can we remove this file, if we keep the `@Test` on the classes like we do?