Provide oFono 1.15 with BlueZ 5 support

oFono provides a mobile telephony (GSM/UMTS) mobile
telephony stack.
When compiled with Bluetooth support, it also compiles
the HFP (Hands Free Profile) plugin, which is actively
required by AGL 1.0 specification (AGL:5.1.1.1).

The "hfp_bluez5" and "hfp_ag_bluez5" plugins are compiled
as we now ship BlueZ 5.

Change-Id: I815d3aeceb02abff624d0223cf0fef46c509014f
Signed-off-by: Manuel Bachmann <mbc@iot.bzh>