React Native Router app Files

Changelog:

• Allow data to be passed to your routes by passing an object with the data key in the toRoute()-function.
• Update Twitter example to show how passing data to your routes is useful.
• Custom actions for your rightCorner and leftCorner components (to do stuff besides navigating to routes, like opening a side menu). This is triggered by calling the callback function this.props.customAction() from your component. It is then picked up with <Router customAction={this.doSomething} />.
• Allow the navigation bar title to be styled with the titleStyle-prop in the <Router /> component.