libwebsockets

http uri arguments process in fragments

This makes the URI argument processing split each parameter into
a "fragment".  Processing header content as fragments already exists
in lws, because it's legal to deliver header content by repeating
the header.

Now there's an api to access individual fragments, also add the
code to the test server to print each URI argument separately.

Adapt attack.sh to parse the fragments.

Signed-off-by: Andy Green <andy.green@linaro.org>