Adding release build task

Author: dfmcphee

package.json

@@ -19,7 +19,8 @@
   "main": "index.js",
   "scripts": {
     "start": "electron .",
-    "build": "electron-packager . $npm_package_productName --out=dist --platform=darwin --arch=x64 icon=Icon.icns --ignore='^/dist$' --version=$npm_package_electronVersion --sign=U7937AY495 --overwrite"
+    "build": "electron-packager . $npm_package_productName --out=dist --platform=darwin --arch=x64 icon=Icon.icns --ignore='^/dist$' --version=$npm_package_electronVersion --overwrite",
+    "build-release": "electron-packager . $npm_package_productName --out=dist --platform=darwin --arch=x64 icon=Icon.icns --ignore='^/dist$' --version=$npm_package_electronVersion --sign=U7937AY495 --overwrite"
   },
   "keywords": [
     "electron-app"