How to modularize router scenes?

### Version
Tell us which versions you are using:

- react-native-router-flux v4.0.6
- react v16.5
- react-native v0.55

### Expected behaviour

Attempting to break huge scene component into separate smaller components, and importing them into the body of the root scene component. Expect to do be able to do something like this:

```
import HomeTab from './HomeTab'
...

return (








```
where `HomeTab` looks like:
```
import React, { Fragment, Component } from 'react';
import { Scene } from 'react-native-router-flux';
import ExplorePage from '../../components/pages/ExplorePage/ExplorePage';
import styles from './styles';
import dictionary from '../../components/constant/dictionary/en_us';
...

export default class HomeTab extends Component {
render() {
return (
} title={dictionary.DISCOVER}>

...

);
}
```
And my expected behavior is the main scene component would pull in this fragment of a scene and render accordingly.

### Actual behaviour

### Steps to reproduce
For non-obvious bugs, please fork this component, modify Example project to reproduce your issue and include link here.
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### Reproducible Demo

Please provide a minimized reproducible demonstration of the problem you're reporting.

Issues that come with minimal repro's are resolved much more quickly than issues where a maintainer has to reproduce themselves.