[2/3] Frameworks: Increasing Ringtone

      Option to set the incoming call ringtone volume to increase
      in pre-defined (user selected) increments.

Linked commits:
      Settings   - https://gerrit.paranoidandroid.co/#/c/447/
      Telephony  - https://gerrit.paranoidandroid.co/#/c/451/

Change-Id: I6314108033089c68c3bd6f716508f40fe863f630