Implement a new representation to get fuller reps of child resources

Add a new standard representation ("expanded", "exploded", "extended", etc.) that would be like full but lists would be represented as defaults or fulls rather than refs. For example, the full rep of location has a list of location attributes in ref rep, the extended rep would have default or full reps of each location attribute.

This is designed to be a quickly implementable way to get more of a hierarchy with a single call. The fact that its an exploded rep would be kept in the request context and accessed only when it's time to represent a list; the representation itself would think it's a full rep.