Add idle timeout choice "Never" to disable idle disconnection (fix #169)

Signed-off-by: Daniele Ricci <daniele.athome@gmail.com>
Fix #171: workaround NPE on Google Play missing

Signed-off-by: Daniele Ricci <daniele.athome@gmail.com>
Fix stuck progress dialog during IAB setup

Signed-off-by: Daniele Ricci <daniele.athome@gmail.com>
Fix #170: consistent menus across API levels

Signed-off-by: Daniele Ricci <daniele.athome@gmail.com>
Use a single SharedPreferences instance (closes #152)

Signed-off-by: Daniele Ricci <daniele.athome@gmail.com>
Merge branch 'master' into audio_message