Copy assets to app directory

package.json

@@ -34,6 +34,7 @@
     "babel-eslint": "6.1.2",
     "babel-loader": "6.2.4",
     "babel-preset-react": "6.11.1",
+    "copy-webpack-plugin": "^3.0.1",
     "electron-builder": "5.17.0",
     "electron-prebuilt": "1.3.1",
     "eslint": "3.1.1",

webpack.config.js

@@ -1,4 +1,5 @@
 const webpack = require('webpack');
+const Copy = require('copy-webpack-plugin');
 const path = require('path');
 
 const nodeEnv = process.env.NODE_ENV || 'development';
@@ -29,7 +30,13 @@ module.exports = {
       'process.env': {
         'NODE_ENV': JSON.stringify(nodeEnv)
       }
-    })
+    }),
+    new Copy([
+      {
+        from: './assets',
+        to: './assets'
+      }
+    ])
   ],
   target: 'electron'
 };