Add a dev build configuration

Add caching and a faster source map for the dev builds.
This brings the rebuild time down to about 500ms for me.

dev build now puts the bundle in the electron app/js directory
so that the app can be automatically reloaded

webpack.config.js

@@ -25,8 +25,8 @@ module.exports = {
     loaders: [
       { test: /\.css$/, loader: "style!css" },
       {
-	    test: /\.jsx?$/,
+	test: /\.jsx?$/,
-	    loader: 'babel',
+	loader: 'babel',
         query: {
           cacheDirectory: true,
           presets:[ 'es2015', 'react', 'stage-2' ]

webpack.dev.config.js

@@ -0,0 +1,41 @@
+const path = require('path');
+
+const PATHS = {
+  app: path.join(__dirname, 'app'),
+  dist: path.join(__dirname, '..', 'app', 'dist')
+};
+
+module.exports = {
+  entry: ['babel-polyfill', './js/main.js'],
+  output: {
+    path: path.join(PATHS.dist, 'js'),
+    publicPath: '/js/',
+    filename: "bundle.js",
+    pathinfo: true
+  },
+  debug: true,
+  cache: true,
+  devtool: 'eval',
+  module: {
+    preLoaders: [
+      {
+        test: /\.jsx?$/,
+        loaders: ['eslint'],
+        // define an include so we check just the files we need
+        include: PATHS.app
+      }
+    ],
+    loaders: [
+      { test: /\.css$/, loader: "style!css" },
+      {
+	test: /\.jsx?$/,
+	loader: 'babel',
+	query: {
+          cacheDirectory: true,
+          presets:[ 'es2015', 'react', 'stage-2' ]
+        }
+      }
+    ]
+  },
+  target: 'electron-main',
+};