Authentication with HTTP Proxy

Possibly user error so happy for you to shoot me down.

I seem unable to use the keybase windows client with a proxy server which requires authentication. Proxy requires username and domain to be passed.

I've fiddled with the --proxy parameter with no success.

Start with the Windows client and reproduce the failure using an HTTP proxy that requires both a username and domain. Trace how the --proxy parameter is handled, and consider the issue complete when authenticated proxy use works with those credentials.

Written by the indexing model from the issue text.