refactor: migrate from browserify to webpack

.babelrc

@@ -0,0 +1,10 @@
+{
+  "presets": [
+    [
+      "@babel/preset-env",
+      {
+        "targets": "> 0.25%, not dead"
+      }
+    ]
+  ]
+}

middleware/webpack.js

@@ -0,0 +1,9 @@
+const webpack = require('webpack')
+const config = require('../webpack.common')
+const webpackDevMiddleware = require('webpack-dev-middleware')
+
+module.exports = () => {
+  return webpackDevMiddleware(webpack(config), {
+    publicPath: config.output.publicPath,
+  })
+}