TUNE-4888 Initial check-in of AUI server GATT profile
TUNE-4889 BLE central devices can connect to the AUI profile

 - Advertising is enabled when no central devices are connected

As part of this, I added the hci_ext module. This extends src/hci.c by
adding support for configuring advertising packets
Added README in AUI profile
TUNE-4890 bluetoothd now communicates remote AUI cmds on dbus
Added a test for AUI advertising enabling

usage: profiles/aui/set-aui-adv hci0 "<adv-string>"
Where <adv-string> cannot be greater then 16 characters