navigationBarStyle in Route doesn't work

For some reason I am unable to override scene NavBar style with `navigationBarStyle` option, as it stated in docs.

My component structure is following:

```
<Router ... navigationBarStyle={styles.bar}>
   <Route name='onboarding' ... navigationBarStyle={styles.bar2} />
</Router>
```

I expect the Onboarding page will have custom NavBar color, but it doesn't.
