Bug 1091588: Add helpers for Bluetooth daemon Handsfree support, r=shuang

This patch adds helpers for packing, unpacking and converting
Handsfree values to and from Bluetooth PDUs.
Bug 1091588: Add Handsfree module for Bluetooth daemon, r=shuang
Bug 1091588: Add Handsfree interface for Bluetooth daemon, r=shuang
Bug 1091588: Support Handsfree profile when using Bluetooth daemon, r=shuang