Return DeleteResponse from ContainerService.Delete

The message was defined but the method was returning empty, plumb through the
result from the shim layer.

Compile tested only.

Signed-off-by: Ian Campbell <ian.campbell@docker.com>

runtime.go

@@ -26,7 +26,7 @@ type Runtime interface {
 	// Containers returns all the current containers for the runtime
 	Containers() ([]Container, error)
 	// Delete removes the container in the runtime
-	Delete(context.Context, Container) error
+	Delete(context.Context, Container) (uint32, error)
 	// Events returns events for the runtime and all containers created by the runtime
 	Events(context.Context) <-chan *Event
 }