Adds full metadata editing for Collections (same DC fields as GenericFiles)

Fixes hydra-editor style partials in views/records.

refs gwu-libraries/gw-sufia#82
refs gwu-libraries/gw-sufia#25
I don't understand the question.  In all cases, the view is relying on the model to decide which DS its attributes map to.  The view just calls .creator and the model dictates whether that delegates to properties or descMetadata.