Response redirect

[maiah]

Provide a redirect method to Response object that can be used by middlewares and user request-handlers.

Proposed usage:

res.redirect('/some/path/here');

[garywu125]

void redirect(url, [int code = HttpStatus.MOVED_TEMPORARILY]) {
_res.statusCode = code;
_res.headers.set('Location', url);
_res.outputStream.close();
}