Update webpack React externals [Fix #11, Fix #8]

src/webpack.config.js

@@ -10,7 +10,12 @@ module.exports = {
   },
 
   externals: [{
-    'react': 'React',
+    'react': {
+      root: 'React',
+      commonjs2: 'react',
+      commonjs: 'react',
+      amd: 'react',
+    },
   }],
 
   module: {