Add REST event sequence discussion

The latest version of Chapter 3 introduces Backbone's RESTful API (fetch, save, destroy, etc.) and Chapter 5 provides a RESTful application tutorial. It would be helpful to follow-up on these with a discussion of what happens and when during these operations (e.g., validation, url construction, events, sync call, success/error callbacks, parsing, model state changes). Recommended location in or adjacent to the RESTful tutorial.