Implement Redux for the ReactPlugin

[mxstbr]

At the moment the PlaygroundList component of the ReactPlugin is a massive beast that takes care of everything. It's like a top level global state management thingy – oh wait, there's better solutions for this? 😉

I think we've discovered the point where integrating Redux starts making sense and everything easier to handle. Would appreciate a PR implementing this!

[lithin]

I'm on it :)