fixed loss of context for 'this' keyword when AppView instance method addAll...

fixed loss of context for 'this' keyword when AppView instance method addAll calls AppView instance method addOne (in the backbone app).

architecture-examples/backbone/js/app.js

@@ -212,7 +212,7 @@ $(function(){
 
 		// Add all items in the **Todos** collection at once.
 		addAll: function() {
-			Todos.each(this.addOne);
+			Todos.each(this.addOne, this);
 		},
 
 		// Generate the attributes for a new Todo item.