AVRCP Statemachine

Refactor AVRCP profile to reflect state machine design as seen in other
bluetooth profiles.  This update will include all features required for
AVRCP 1.3 along with absolute volume control from 1.4.  Interface logic
will be seperated out into the Service class and policy logic will be
maintained within the StateMachine.

bug: 28671900
Change-Id: I710bac73e3113a7729f449ea9dbb854ceb2438fb