Support GATT services over BR/EDR.

Preview at https://rawgit.com/WebBluetoothCG/web-bluetooth/support-bredr/index.html

@armansito
We should probably add a note somewhere that the UUIDs that are present in the AD may not be an exhaustive list of all GATT services that are exposed by the device and that a connection must be established to discover all GATT services over ATT.