WARNING: If you have a phone it's possible that rotation won't work on your homescreen(launcher), but it will work in apps, I promise.
This is an open-source application, with code available on https://github.com/Manuiq/Angle
WRITE_SETTINGS - to change orientation
RECEIVE_ON_BOOT_COMPLETE - to launch notification on system startup
Version 1.01 works well. Easy to use. Can change rotation from pulldown notification list or from screen lock.