Add a method to tag the AuthStatus as disconnected and redirect to a login URL

[bgaillard]

Sometimes when we receive an error un the parseErrorFn we simply want to mark the AuthStatus as disconnected and redirect the user to a separate login page.

For now the parseErrorFn function has only one xhr argument, this is not powerful enough because it does not offer an access to other useful objects like the current requestContext.

Refactor the parseErrorFn function :

• Change the xhr argument with something which give access to more informations and functions.
• Implement something like requestContext.getAuthStatus().logoutAndRedirect('http://localhost/login');

Finally I'm wondering if the loginFn method is really useful as a developer could easily add a call to its login form directly in the parseErrorFn method and simply call the OAuth.sendCredentials() method again.