Power save mode with ignoring events in muted rooms

Current Riot-Android in background mode receive all events, even in muted rooms. This is not good for traffic & battery.

For example, I joined to `Matrix HQ`, `Riot` and some others active rooms, because very rarely read them (1-2 times in week). But my mobile device wakes up and receive every message from those rooms, eating my battery and traffic.

Will be good to implement power save mode, that receive only events for active rooms and ignore muted rooms, sync them only on demand (when they opened manually).