Upgrading to webpack 4 & the new webpack blocks so that we can get ready for storybook 4

[Paul Letkeman]

Hi Diego,
Really love this project scaffold. I have modified it with pug js templates and it works nicely both in the server as well as within storybook. I would really like to start future proofing this stuff now as there are some really nice features appearing in storybook (html based stories) that will not work properly as the configuration is shared. As such I was wondering if you would like to help me create a webpack 4 branch of this project .... there are a couple of places where I am sure I will get stuck and will probably need your help with. The current branch I am working in is the redux-ssr branch ... but when it comes to a system wide upgrade I am sure there is a better branch to get started with and then merge from.

Thank you for making this project public and I look forward to helping you work on the upgrade.