Added BLE Radio on/off scanning.

[btetz14]

This adds BLE Radio on/off scanning. With a small update to bindings.js, noble.on stateChange will work.

This is the update needed to bindings.js

        case 'Start':
            this.state = 'poweredOn';
            this.emit('stateChange', this.state);
            break;
        // add this case below 'Start' in bindings.js
        case 'Stop':
            this.state = 'poweredOff';
            this.emit('stateChange', this.state);
            break;

[urish]

Thanks, please have a look at my comments

[urish]

Please change to "start" and "stop" (camelCase) to keep consistent with the other values for _type

[urish]

This exact same code repeats a few lines above. I'd refactor it into a function that gets the radio state, creates the message and calls writeObject. In addition, you can write it more concisely as:

JsonObject^ msg = ref new JsonObject();
if (sender->State == Windows::Devices::Radios::RadioState::On) {
    msg->Insert("_type", JsonValue::CreateStringValue("start"));
} else {
    msg->Insert("_type", JsonValue::CreateStringValue("stop"));
}
writeObject(msg);