Add support for Observable emitting additional "thunkservables"?

[benlesh]

Okay... so I just coined a term "thunkservable"... which is a function that returns an observable.

Anyhow, should we support something like this?

let secondAction = () => Observable.of({ type: 'ACTIONS_DONE' });
let firstAction = () => Observable.interval(1000).mapTo(secondAction);

dispatch(firstAction);

[benlesh]

cc/ @jayphelps