message: update to electron 1.6.8
diff: "babel-preset-es2015": "^6.24.0",
  "browserify": "^14.1.0",
  "cross-env": "^3.2.4",
  - "electron": "1.6.7",
  + "electron": "1.6.8",
  "electron-builder": "^13.9.0",
  "electron-builder-squirrel-windows": "^12.3.0",
  "electron-packager": "^8.5.2",
  