Not able to disable proxy

I looked at the options in the `keybase help advanced` command, but I can't find a way to **disable** my proxy settings. I've put in `--proxy=""` in hopes that it would unset it, as well as unsetting my `$http/s_proxy` environment variable, but no matter what, I still get an error with it trying to go through the proxy:

```
C:\Users\Me > keybase --proxy="" login
- WARNING Failed to register as a logger: The handle is invalid.
- ERROR Access is denied.
C:\Users\Me > keybase login
Your keybase username or email address: klauern
- ERROR API network error: Get https://keybase.io/_/api/1.0/user/lookup.json?fields=basics%2Cpublic_keys%2Cpictures&multi=1&username=klauern: http: error connecting to proxy http://myproxy.somewhere.com:80: dial tcp: lookup myproxy.somewhere.com: getaddrinfow: No such host is known. (error 1601)
```

Start with the `keybase help advanced` output and the `keybase login` path shown in the report, then trace how `--proxy` and the `http/s_proxy` environment variable are read. Done means users can explicitly disable the configured proxy and `keybase login` connects directly, while normal proxy configuration still works.

Written by the indexing model from the issue text.