Set in stone the port number and improve app message on launch

[igorwojda]

1. Port value is set in stone, so user can easily refresh the page without wondering about the port number (actually URL) on subsequent launches

2. Message after launching the app is improved Old: Your app is listening on port 3200 New: App available at: http://localhost:3200/

Benefits of new message:

• Consistent with our server.js approach from tutorial samples
• Present exact app url to the user, not only port
• Terminal allows cmd+click to open app in the browser

[igorwojda]

We have to investigate fixed port behavior with local run vs Heroku vs gitch

[igorwojda]

Closed - this would fail after heroku depoyent