private void sendRegistrationToServer(String token) {
        Log.i(TAG, "GCM Registration Token: " + token);
    }
Normally, you would want to persist the registration to third-party servers. Because we do
not have a server, and are faking it with a website, you'll want to log the token instead.
That way you can see the value in logcat, and note it for future use in the website.

@param token The new token.
app/src/main/java/com/example/android/sunshine/app/gcm/RegistrationIntentService.java