Webpack - vendor code splitting.

[awitherow]

Currently I believe the hot module loader is broken and does a force refresh because of bootstrap. This is due to vendor code not being split into another file by webpack.

related documentation:

• https://webpack.js.org/guides/code-splitting-libraries/
• https://webpack.js.org/guides/hmr-react/
• https://webpack.js.org/configuration/dev-server/