This adds a demonstration of how to use the http nonblocking
send action to the test server.
If you ask for /leaf.jpg from the test server, it will send
"by hand" a 2.4MB jpeg in HTTP, including the headers. See
the test server sources to see how it is done.
Although it's a file, and a jpeg image, actually the exact
same scheme will work for any data or mime type.
Signed-off-by: Andy Green <andy.green@linaro.org>