Document the 'Snap.Test' module.

Yuck. What do you think about improving the output of the Show instance while you are doing this? I would prefer that to happen rather than this regurgitation ever making it into the comments.

The status line and headers can be printed much more compactly. This request would look better as something like:

    GET /foo/bar HTTP/1.1
    host: localhost
    
    sn="localhost" c=127.0.0.1:60000 s=127.0.0.1:8080 ctx=/