Define semantics for PUT against a single entity with nested content

Align Semantics of PUT with PATCH, as specified in ODATA-876 , by specifying that, when you do a PUT, 1) You can include new nested entities, existing entities, and references to existing entities 2) Existing entities are updated using PUT semantics a) entities to be updated must have either @odata.id or key fields, otherwise interpreted as an insert b) if @odata.id and key fields both exist but don't match, then request is invalid 3) The end result of the PUT is that the specified entities and entity references are the full set of entities related according to that relationship.