Added proxy support and more verbose error logging.

If a user has defined `http_proxy` environment variable, then set
the corresponding `proxy` option in the HTTP request. This allows
users behind a proxy server to use this package.

In addition, added more verbose error logging by including the
HTTP response object, `res`, in the console output. While testing
this new functionality, I encountered an error from stackexchange
due to rate limiting of requests coming from the corporate proxy
server. This was only apparent after examining the HTTP response
object, which contained the true reason for failure, so I've now
included the response object in the console logging.
Merge pull request #10 from pkazmier/proxy-support

Added proxy support and more verbose error logging.
Fixes #9