message: Make the build scripts support rebuilding native modules for electron's V8 API
  package.json now references a local git repo and build of
  When `electron-rebuild` has
  merged then we need to point to the new version of `electron-rebuild`.
diff: "build-extensions": "npm run npm-install-extension-api ; node src/build_scripts/npm_extensions.js build",
  "build-icons": "node src/extra_icons/build.js",
  - "npm-install-all": "npm install ; npm run npm-install-extensions",
  + "npm-install-all": "npm install ; npm run npm-install-extensions ; npm run electron-rebuild",
  "npm-install-extension-api": "npm install extraterm-extension-api ; node src/build_scripts/npm_extensions.js install-extension-api",
  "npm-install-extensions": "node src/build_scripts/npm_extensions.js install",
  + "electron-rebuild": "node ./node_modules/electron-rebuild/lib/src/cli.js -o ptyw.js,font-manager -f -v 1.6.8",
  +
  "testbulkdomoperation": "npm run build ; nodeunit src/BulkDomOperationTest.js",
  "testextensionloader": "npm run build ; nodeunit src/ExtensionLoaderTest.js",
  "testkeybindingmanager": "npm run build ; nodeunit src/KeyBindingManagerTest.js",
  "cajon": "0.2.10",
  "electron": "1.6.8",
  "electron-packager": "8.7.0",
  - "electron-rebuild": "1.5.7",
  + "electron-rebuild": "file:../electron-rebuild/",
  "finalhandler": "0.4.0",
  "modclean": "2.1.0",
  "nodeunit": "0.11.0",
  