Add sourcemaps support for placeholder app

app/package.json

@@ -5,7 +5,8 @@
   "main": "lib/main.js",
   "dependencies": {
     "electron-window-state": "^2.0.0",
-    "wurl": "^2.1.0"
+    "wurl": "^2.1.0",
+    "source-map-support": "^0.4.0"
   },
   "devDependencies": {},
   "scripts": {

app/src/main.js

@@ -2,6 +2,8 @@
  * Created by JiaHao on 4/7/15.
  */
 
+import 'source-map-support/register';
+
 var fs = require('fs');
 var path = require('path');
 var electron = require('electron');

webpack.config.js

@@ -28,5 +28,6 @@ module.exports = {
         loaders: [
             {test: /\.js$/, exclude: /node_modules/, loader: 'babel-loader'}
         ]
-    }
+    },
+    devtool: 'source-map'
 };