Will be nice to clear auth credentials. For example, I'm using a proxy that accepts options via username:

```
proxy.com:8080
user: wiliam_country_US
```

So, if I want to change the peer node, I change my username:

```
proxy.com:8080
user: wiliam_country_GB
```

But, I'm not changing the proxy, so electron has valid credentials and is not going to trigger `login` event.

I'm searching the way to clean auth settings so electron asks them again.
atom/browser/net/atom_url_request.cc
DCHECK_CURRENTLY_ON(content::BrowserThread::IO);
  if (!request_) {
    return;
  }
  request_->CancelAuth();
}
void AtomURLRequest::DoCancelWithError(const std::string& error,
                                       bool isRequestError) {
  DoCancel();
  content::BrowserThread::PostTask(
      content::BrowserThread::UI, FROM_HERE,
      base::Bind(&AtomURLRequest::InformDelegateErrorOccured, this, error,
                 isRequestError));
}
void AtomURLRequest::OnAuthRequired(net::URLRequest* request,
                                    net::AuthChallengeInfo* auth_info) {
  DCHECK_CURRENTLY_ON(content::BrowserThread::IO);
  content::BrowserThread::PostTask(
      content::BrowserThread::UI, FROM_HERE,
      base::Bind(&AtomURLRequest::InformDelegateAuthenticationRequired, this,
                 scoped_refptr<net::AuthChallengeInfo>(auth_info)));
}
void AtomURLRequest::OnResponseStarted(net::URLRequest* request) {