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/api/atom_api_url_request.h
namespace api {
class URLRequest : public mate::EventEmitter<URLRequest> {
 public:
  static mate::WrappableBase* New(mate::Arguments* args);
  static void BuildPrototype(v8::Isolate* isolate,
                             v8::Local<v8::FunctionTemplate> prototype);
  
  void OnAuthenticationRequired(
      scoped_refptr<const net::AuthChallengeInfo> auth_info);
  void OnResponseStarted(
      scoped_refptr<net::HttpResponseHeaders> response_headers);
  void OnResponseData(scoped_refptr<const net::IOBufferWithSize> data);
  void OnResponseCompleted();
  void OnError(const std::string& error, bool isRequestError);
 protected:
  explicit URLRequest(v8::Isolate* isolate, v8::Local<v8::Object> wrapper);
  ~URLRequest() override;
 private:
  template <typename Flags>
  class StateBase {