Fix appveyor build script

Author: kriskbx

appveyor.yml

@@ -24,5 +24,5 @@ version: '{build}'
 shallow_clone: true
 clone_depth: 1
 test_script:
-- ps: webpack --progress --hide-modules --config=node_modules/laravel-mix/setup/webpack.config.js
+- ps: yarn run production-windows
 - ps: yarn run publish

mix-manifest.json

@@ -1,4 +1,4 @@
 {
-    "/src/build/app.js": "/src/build/app.js",
+    "/P:/src/build/app.js": "/P:/src/build/app.js",
     "/src/build/app.css": "/src/build/app.css"
 }

package.json

@@ -13,7 +13,8 @@
     "dev": "NODE_ENV=development webpack --progress --hide-modules --config=node_modules/laravel-mix/setup/webpack.config.js",
     "watch": "NODE_ENV=development webpack --watch --progress --hide-modules --config=node_modules/laravel-mix/setup/webpack.config.js",
     "hot": "NODE_ENV=development webpack-dev-server --inline --hot --config=node_modules/laravel-mix/setup/webpack.config.js",
-    "production": "NODE_ENV=production webpack --progress --hide-modules --config=node_modules/laravel-mix/setup/webpack.config.js"
+    "production": "NODE_ENV=production webpack --progress --hide-modules --config=node_modules/laravel-mix/setup/webpack.config.js",
+    "production-windows": "node node_modules/cross-env/dist/bin/cross-env.js NODE_ENV=production node_modules/webpack/bin/webpack.js --progress --hide-modules --config=node_modules/laravel-mix/setup/webpack.config.js"
   },
   "keywords": [],
   "author": "Kris Siepert",
@@ -120,6 +121,7 @@
     "babel-plugin-transform-async-to-generator": "^6.24.1",
     "babel-preset-env": "^1.6.1",
     "babel-preset-react": "^6.24.1",
+    "cross-env": "^5.2.0",
     "electron-forge": "^5.0.0",
     "electron-prebuilt-compile": "1.7.11",
     "eslint": "^3",