Bug 1072811 - [Bluetooth] BluetoothHelper APIv2 support

* patch bluetooth_helper
* revice bluetooth mockup
* add uitest/HW/bluetooth for demo
In API version 2, there is no `adapteradded` event for Gaia listener. We have to use `mozBluetooth.onadapteradded` to handle following user story.

Ref: https://wiki.mozilla.org/B2G/Bluetooth/WebBluetooth-v2/BluetoothManager#onadapteradded