We want to revive golang.org/x/example as a test case for
an experiment with a 'gonew' command.

This CL updates outyet to be a gonew-able sample server,
by making it its own module. The CL also removes
Dockerfile and containers.yaml because I think the
best practices around those files have evolved too much
since 2015 when they were written.

Change-Id: I53faf4b30de9e4ef3bfe35a781732daa140a9877
Reviewed-on: https://go-review.googlesource.com/c/example/+/513998


TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Russ Cox <rsc@golang.org>
Auto-Submit: Russ Cox <rsc@golang.org>
Reviewed-by: Cameron Balahan <cbalahan@google.com>