Update Marionette section

I've updated the Marionette code to use `listenTo` instead of `bindTo` and adjusted the surrounding text, accordingly. 

I've also removed the list of components / links in favor of a generalized paragraph explaining some of the core parts. The list of components changes too often for it to be meaningful in this book.

And I've adjusted a few other misc things, like not using @ gmail.com for email addresses.