*Service: Don't rely on intents for important status updating.

In this case, we can't rely on intents to keep the status up to date about
whether the StreamingService is wound down, as they're WAY too slow which
then causes a race for audio focus. Instead use static values and public
accessor.
StreamingService: Abandon audio focus when winding down resources.
StreamingService: Improve focus code.

Turns out the transient focus code doesn't work in the more recent Android,
maybe never? At any rate, fixed transient focus and added some more improved
methods of dealing with focus with regard to streaming.