Use -p flag in webpack for minification and exclude externals react and react-dom (#159)

Author: doque

scripts/build

@@ -1,2 +1,2 @@
 #!/bin/sh
-webpack --config webpack.dist.config.js
+webpack --config webpack.dist.config.js -p

webpack.dist.config.js

@@ -9,6 +9,11 @@ module.exports = {
     'react-modal.min': './lib/index.js'
   },
 
+  externals: [
+    'react',
+    'react-dom'
+  ],
+
   output: {
     filename: '[name].js',
     chunkFilename: '[id].chunk.js',
@@ -37,4 +42,4 @@ module.exports = {
     ]
   }
 
-};
+};