handsfree-audio: Initial DBUS code

This code can register an handsfree audio agent and receive NewConnection and
Release calls.
handsfree-audio: Build handsfree-audio command line tool
handsfree-audio: Add Alsa dependancy
handsfree-audio: Add SBC dependency
handsfree-audio: Link tool with Alsa
handsfree-audio: Implement alsa playback
pending