Re-implement react-hot-loader

[KevinGrandon]

Type of issue

Feature request

Description

In #284 we have removed references to the react-hot-loader as it was not playing nicely with the Webpack4 and babel7 upgrade. Since we have a HMR handler in client-entry.js, we currently have HMR, but do not have react-hot-loader logic. We should investigate if we can add react-hot-loader back in a way that is auto-instrumented for all Fusion.js applications.

What will this give us?

This will enable us to have hot react component reloading which will maintain component state across reloads. This should also be more performant than full app HMR.

Redux state restoration

Today we throw away the entire app and re-generate it, but we have some logic that persists redux state. Even if we throw away the entire application, the experience is still nice because of the persisted redux state. This is great for folks using redux, but not as good for people who don't.

Deliverables

• Integration test for hot loading, ensure state doesn't change.
• Add react-hot-loader and have this automatically work with components by default.