Update the FORM authentication mechanism so it can be configured to redirect to specific location after authentication.

The current implementation caches the intercepted location that the user was attempting to access and after authentication sends them back to that location - this feature request is to support additional configuration to send them to a pre-defined location i.e. some form of welcome page.

Note: Request suspension should probably also be disabled for this mode as if the user is not being directed back to the page they requested there is no point saving and restoring any additional data associated with that request.