2016-12-17 v.1.7.2 - Fixed some more problems and crashes with pre-KitKat devices.
2016-12-17 v.1.7.1 - Fixed more problems and crashes, support for per contacts ringtones, added support for runtime permissions.
2016-12-09 v.1.6.2 - Fixed several issues, and added support for Android 7.
2016-05-03 v.1.6.1 - To all current users - no need to upgrade. Trial period is introduced, and if it works, the user can purchase the app.