Apple TV app needs better user logout / timeout handling

[gthrift 64]

I've noticed that when I come back to a TV that has been idle for quite some time, the last user is still logged in, even when "Show login screen" is selected.   This can include when the app is left up (idle/with no media playing) for an extended time, when the Apple TV is placed into Standby, or when the app has been in the background and another app has been in use.  It happens to both pin protected accounts and unprotected accounts.