libwebsockets

introduce attack script

Seems like it would be a good idea to try to mess with the
server at least before someone else does it for us

Just run the script

$ test-server/attack.sh

it will spawn a test server and fire things at it.  If you
see the end result

---- survived

then you should be OK.

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