_sort should be able to take parameters for non-bundle types

(User Story, Closed -> Fixed, Priority: Critical, Test Status: No automated tests yet , Reported By Justin du Coeur, )

Summary: If you say _sort(func -> func -> func), that all works as expected for Things and other sorts of PropertyBundles. But the parameters are ignored for other data types.

The motivating use case here is that I want to be able to say _thingConversations -> _sort(_latestCommentTime). This drives home that there is more to _sort parameters than simple Property fetches.