Add support for using bypass binding declarations on iterated items.

@@ -88,6 +88,7 @@ class Rivets.Binding
 
   # Unsubscribes from the model and the element.
   unbind: =>
+    unless @options.bypass
       Rivets.config.adapter.unsubscribe @model, @keypath, @set
 
       if @options.dependencies?.length