Fix backbone remaining items counter

This reverts commit 9d4b0b06.

The simplified function call changes the semantics of it. The signature of
without is: _.without(array, [*values]), which is why apply must be used here.

architecture-examples/backbone/js/collections/todos.js

@@ -25,7 +25,7 @@ var app = app || {};
 
 		// Filter down the list to only todo items that are still not finished.
 		remaining: function() {
-			return this.without(this.completed());
+			return this.without.apply( this, this.completed() );
 		},
 
 		// We keep the Todos in sequential order, despite being saved by unordered