[Ready] Isomorphic form processing

[charypar]

This will implement the isomorphic form processing as naturally as possible.

See #1 and redbadger/react-fw-app#10

To-do

• [x] basic server side POST handling
• [x] virtual render and find the form component
• [x] fire event handlers
• [x] 302 redirect with reflex.redirect
• [x] page.js redirect with reflex.redirect
• [x] support all types of form inputs
• [x] refactor routing/rendering functions in `application.

  Missing for full use-case support

• [ ] asynchronous state observers (+ app state transactions) - that will probably be a separate PR

[tabazevedo]

After reading it through, my confusion was clarified. It will be strange using React without requiring it but I'll live with it for the sake of progress! Merging.

[charypar]

@tabazevedo this was necessary, unfortunately. All the injections in server-rendering.ls need to happen on the same instance of React the app is using.

And there is a much deeper issue with that reported in React where multiple instances are created by each package depending on React...