Basic infrastructure of HMR

[3cp]

Based on the idea from https://medium.com/@the1mills/hot-reloading-with-react-requirejs-7b2aa6cb06e1

• Support module.hot in dumber-module-loader
• Support HMR in dumber
• Hook up https://github.com/aurelia/hot-module-reload
• Hook up https://github.com/gaearon/react-hot-loader
• TBD vueify hot reload? maybe need to wait for dumberify

[3cp]

Still got no desire to implement hmr.

Even with hmr implemented in dumber and dumber-module-loader, aurelia/react hot reload cannot cover all edge cases (such as router config). I don't want to implement a feature that brings in more troubles than it solves.

[3cp]

Let's put it back, in case I got time for it.