Allow clients to determine the difference between create or update on PUT

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.

pkg/apiserver/interfaces.go

@@ -41,10 +41,27 @@ type RESTStorage interface {
 	// Delete finds a resource in the storage and deletes it.
 	// Although it can return an arbitrary error value, IsNotFound(err) is true for the
 	// returned error value err when the specified resource is not found.
-	Delete(ctx api.Context, id string) (<-chan runtime.Object, error)
+	Delete(ctx api.Context, id string) (<-chan RESTResult, error)
 
-	Create(ctx api.Context, obj runtime.Object) (<-chan runtime.Object, error)
-	Update(ctx api.Context, obj runtime.Object) (<-chan runtime.Object, error)
+	// Create creates a new version of a resource.
+	Create(ctx api.Context, obj runtime.Object) (<-chan RESTResult, error)
+
+	// Update finds a resource in the storage and updates it. Some implementations
+	// may allow updates creates the object - they should set the Created flag of
+	// the returned RESTResultto true. In the event of an asynchronous error returned
+	// via an api.Status object, the Created flag is ignored.
+	Update(ctx api.Context, obj runtime.Object) (<-chan RESTResult, error)
+}
+
+// RESTResult indicates the result of a REST transformation.
+type RESTResult struct {
+	// The result of this operation. May be nil if the operation has no meaningful
+	// result (like Delete)
+	runtime.Object
+
+	// May be set true to indicate that the Update operation resulted in the object
+	// being created.
+	Created bool
 }
 
 // ResourceWatcher should be implemented by all RESTStorage objects that