Sustain future updates

[UweTrottmann]

• [ ] ~Allow to subscribe on Amazon even if pass purchased, add info message like for Play~ Not with this.
• [ ] ~Add explicit list of subscription features in-app (no one visits the website)~ Not with this. Also not sure, main purpose is to support me.
• [x] Display star icon in more places, like Cloud sign-in (check where Utils.advertiseSubscription() is called)

Not with this, but: think about introducing a new in-app one-time purchase that does not include Cloud (which has the highest recurring costs).