message: rename app name to petmate
  linux build uses this field
diff: {
  - "name": "electron-react-boilerplate",
  - "productName": "electron-react-boilerplate",
  + "name": "petmate",
  + "productName": "petmate",
  "version": "0.1.0",
  "description": "C64 PETSCII Editor",
  "main": "./main.prod.js",
  