Add option for non sogou proxy servers // FREEBIE

To use non sogou proxy servers, use `--proxy-list` like:
    nodejs droxy.js --proxy-list myproxy.com,you.proxy.net

Also fix a bug where DNS lookup fails if chroot was called.
Merge pull request #296 from mozbugbox/dns-reverse-proxy-non-sogou-proxy

Add option for non sogou proxy servers // FREEBIE