samba: enable back avahi support, this partly reverts https://github.com/OpenELEC/OpenELEC.tv/commit/d314594b, this should fix #2339

Signed-off-by: Stephan Raue <stephan@openelec.tv>
bluez: add and install obexd dbus service file

Signed-off-by: Stephan Raue <stephan@openelec.tv>