Disable minification for server-side code

No real reason to do this since we won't send this JS anywhere.
When Express fails, it will point to a sensible line instead of dumping the entirety of main.js into the log.

webpack/webpack.prod.ts

@@ -17,4 +17,7 @@ module.exports = Object.assign({}, commonExports, {
   recordsOutputPath: projectRoot('webpack.records.json'),
   entry: projectRoot('./server.ts'),
   target: 'node',
+  optimization: {
+    minimize: false
+  },
 });