title: RNRF and displaying a scene based on redux store state
body: <p>I've got a app that has a collection of scenes, and make many calls to a remote server that because they control hardware can take quite a while.  In my redux store I have a variable that represents if there are any requests inflight. </p>
  
  <p>What I'm trying to achieve is having a spinner or loading scene defined in a single place, and having automatically show dependent on the state of variable in the redux store.</p>
  
  <p>I think that the answer lies in having a <code>modal</code> scene for the loading page, but the bit I'm missing is how to have it automatically displayed (and hidden) based from the state in the store.  I don't want to call <code>Actions.loadingScene()</code> from all the places that makes the requests.</p>
  
  <p>I've got a reducer in place that see's all the actions (both the application and the RNRF actions), but I couldn't work how what state I had to mutate to get it to display the modal scene.</p>
  
  <p>Any pointers would be great!.</p>