message: Update the version of electron-packager.
diff: "devDependencies": {
  "cajon": "0.2.10",
  "electron": "1.4.12",
  - "electron-packager": "7.3.0",
  + "electron-packager": "8.4.0",
  "electron-rebuild": "1.4.0",
  "finalhandler": "0.4.0",
  "nodeunit": "0.9.1",
  