Can successfully run Webpack to create dist/bundle.js

The bundled output is noticeably different; likely due to Webpack 4
vs. 2/3. The order of dependencies also appears to have changed.
The overall output *seems* to be the same. Unsure how to full test
that everything is getting bundled appropriately.

This also allows the project to be built without having to manually
copy files into node_modules.

package.json

@@ -76,7 +76,8 @@
     "url-loader": "~0.5.0",
     "val-loader": "^1.0.2",
     "vm-browserify": "~0.0.0",
-    "webpack-cli": "^2.0.9",
+    "webpack": "^4.1.1",
+    "webpack-cli": "^2.0.12",
     "webpack-dev-middleware": "^1.9.0",
     "worker-loader": "^0.8.0"
   },