Routing management

[lucaantonelli]

Implemented a routing management system and added named routes.

Example for using it: You want to navigate to '/settings' > Navigator.of(context).pushNamed('/settings');

Adding a new route inside routes.dart:

 case '/example':
      return _materialPageRoute(settings.name, ExamplePage());

There is 3 different types of page route animation:

• _cupertinoPageRoute
• _materialPageRoute
• _noTransitionPageRoute

[FedericoBruzzone]

LGTM! :D

Can I merge this stuff?