Getting vendor IDs

[Mauville]

I've got a bootleg Arduino with the CH340G chip. I had some difficulty finding the correct vendorID for my board (it ran perfectly on the CH34x apk), but I managed to find it by scruffily printing every USB device on the TextView:

    @Override
    protected void onStart() {
        super.onStart();
        arduino.setArduinoListener(this);
        UsbManager usbManager = (UsbManager) this.getSystemService(Context.USB_SERVICE);
        display(usbManager.getDeviceList().toString());
    }

I don't know enough about Android development to create a pull request and not botch the app, but I think the project could benefit from helping new people find their vendor ID. It could also help with GH-16 or GH-19.