Phonebook functions for BlueZ

Hello,

I have analyzed the data traffic of my car handsfree set and implemented
the functions for the phonebook retrieval via the CPBR and CPBS
commands. In addition, I added a telephony driver for the FSO middleware
with which I tested the new functions using a Parrot CK3100 car kit and
a Jabra ear plug using version 4.61 of BlueZ. The other telephony
drivers just have empty functions that reject the new commands in order
not to break the APIs.

Attached is the patch file for the git repository.

Felix Huber