Switch electron.js to typescript

package.json

@@ -2,12 +2,12 @@
   "name": "MQTT-Explorer",
   "version": "0.0.7",
   "description": "Explore your message queues",
-  "main": "electron.js",
+  "main": "dist/electron.js",
   "scripts": {
     "start": "electron .",
     "install": "cd app; npm install; cd ..",
     "test": "npm run test-backend",
-    "build": "cd app; npm run build; cd ..; cd backend; npm run build; cd ..",
+    "build": "tsc && cd app && npm run build && cd ..",
     "test-backend": "cd backend && npm run test && cd ..",
     "prepare-release": "./prepare-release.sh",
     "package": "ts-node package.ts",