The pending codec -> conversion split changes the signature of
Encode and Decode to be more complicated. Create a stub helper
with the exact semantics of today and do the simple mechanical
refactor here to reduce the cost of that change.
PUT allows an object to be created (http 201). This allows REST code to
indicate an object has been created and clients to react to it.
APIServer now deals with <-chan RESTResult instead of <-chan runtime.Object,
allowing more data to be passed through.
