title: Providing root reducer in @ngrx/store 4.0
body: <p>In @ngrx/store 2.0 we could provide the root reducer as a function and from there we split our logic inside the application. After I updated to @ngrx/store 4.0 I cannot use this feature any more from what I can see the reducers need to be a map of reducers which will create objects under the same keys in the state. Is there a way to use the old behavoir in @ngrx/store 4.0 In my state components are aware one of another and I need to be able to split my state dynamically also I need to be able to dispatch actions to the right reducer in my own way. Also app is splitted in multiple lazy loaded routes which in some cases reuse the data from another feature.</p>
  
  <pre><code> StoreModule.provideStore(reducer, {
        auth: {
          loggedIn: true
        }
      })
  
  StoreModule.forRoot(reducers, {
        initialState: {
          auth: {
            loggedIn: true
          }
        }
      })
  </code></pre>
  
  <p>I need <code>reducers</code> to be a function which gets the full state and dispatches it to the correct reducer, Is there a way to achieve this behavior?</p>