Add middleware to coordinate router with redux

The router implementation is quite elegant, but it is standalone, what if add a middleware implementation to coordinate it with Redux, just like what [react-router-redux](https://github.com/reactjs/react-router-redux) does.

Review the existing standalone router implementation and the react-router-redux reference linked in the issue. Clarify which router state and Redux actions must be coordinated, then define the integration behavior and tests that would demonstrate it is complete.

Written by the indexing model from the issue text.