Minor tweaks to recent updates, added discussion to go with new diagram

Mostly minor tweaks to recent changes, such as making the example for Backbone.Validate parallel to the preceding example (using User object and firstName attribute). Also, changed the option passed to navigate from 'navigate' to 'trigger' as that appeared to match what is in Backbone (but I haven't actually tried it out).

I added some discussion around the new diagram for client-side MVC. **Please review this closely and make sure that it is correct!**

BTW, the new diagrams are great! I did have one question: is the input to the Router actually an HTTP Request or does it intercept the request URL before it gets to that point?