Improve instructions for using with Immutable.js (#416)
Improve instructions for using with Immutable.js (#416)

1. It was easier for me to think of the reducer by first knowing where
the state was expected to be. Writing it the other way around was
confusing
2. Add that the action payload data must go into the 
`locationBeforeTransitions` property

#415
reactjs/react-router-redux,rackt/redux-simple-router