FMRadio: Add base support for media buttons

* You can use media buttons on your headset to work with FM radio
  (recording of FM stations via media buttons yet not implemented).

1. play/pause or stook buttons allow to pause/play fm radio
2. previous/next track buttons,also as rewind with long press buttons allows to move between stations,find by autoscan .
3. Rewind buttons allows to move between frequences.
4. stopp button should stopp fm service.

Change-Id: I4d86f3e9004d4669c1158f982d6f4564a11edb74