net: add local address/port for better errors

Adds localAddress and localPort to req so we have better error messages.
Also fixes a case where ex is used before it is declared.

PR-URL: https://github.com/nodejs/node/pull/3946


Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Evan Lucas <evanlucas@me.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>