Release of BlueZ 5.6

This is mostly a bug fix release with improvements to AVRCP, A2DP and OBEX. There is also a new command line tool for controlling remote media players (through AVRCP). This release also further improves our user space Bluetooth controller and host emulation which is mainly used for L2CAP end-to-end tests (tools/l2cap-tester). The btmon tool has also received a more complete set of ATT decoders.