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.h
#ifndef ATOM_BROWSER_NET_ATOM_URL_REQUEST_H_
#define ATOM_BROWSER_NET_ATOM_URL_REQUEST_H_
#include <string>
#include <vector>
#include "atom/browser/api/atom_api_url_request.h"
#include "atom/browser/atom_browser_context.h"
#include "base/memory/ref_counted.h"
#include "base/memory/weak_ptr.h"
#include "net/base/auth.h"
#include "net/base/chunked_upload_data_stream.h"
#include "net/base/io_buffer.h"
#include "net/base/upload_element_reader.h"
#include "net/http/http_response_headers.h"
#include "net/url_request/url_request.h"
#include "net/url_request/url_request_context_getter_observer.h"
namespace atom {
class AtomURLRequest : public base::RefCountedThreadSafe<AtomURLRequest>,
                       public net::URLRequest::Delegate,
                       public net::URLRequestContextGetterObserver {
 public:
  static scoped_refptr<AtomURLRequest> Create(
      AtomBrowserContext* browser_context,
      const std::string& method,
      const std::string& url,