Models::Md2d use long path for id, use short path for local_ref_id.
Interactive : use predictable non-varying id's for couch resources.
parsing_spec : deep assertions about Interactive's data-hash
BaseDataObject: Add methods to help find missing CouchDB properties.
Interactive : New properties from interactive-metadata.js
Interactive : associate with Group
Models::Md2d Add missing properties
InteractiveModel maps an Interaction to a Model::Md2d with attributes.

TODO: Easily handle multiple model types. (polymorphic associations)