Added passing down of props from Navigator to the components

[jschfflr]

Added passing down of props to allow loading things once for every screen of the app.

const Navigator = SwipeNavigator({
   ...
});

export default class App extends Component {
  componentDidMount() {
    this.setState({
      user: ...
    })
  }

  render() {
    return (<Navigator user={this.state.user} />);
  }
}