deps: make node-gyp fetch tarballs from iojs.org

Apply a small patch that makes node-gyp fetch the tarballs from
https://iojs.org/ instead of http://nodejs.org/

A patch better suited for inclusion upstream will be put together
shortly.

PR-URL: nodejs#343
Reviewed-By: Rod Vagg <rod@vagg.org>

Author: bnoordhuis