Add scripts for getting/setting firmware variables (#734)

packages/usb/get-variable.js

@@ -0,0 +1,11 @@
+#!/usr/bin/env node
+
+const uhk = require('./uhk');
+const device = uhk.getUhkDevice();
+const sendData = new Buffer([uhk.usbCommands.getVariable, +process.argv[2]]);
+
+console.log(sendData);
+device.write(uhk.getTransferData(sendData));
+const receivedBuffer = Buffer.from(device.readSync());
+console.log(receivedBuffer[1]);
+