Port ctr to use client

Signed-off-by: Michael Crosby <crosbymichael@gmail.com>

task.go

@@ -52,6 +52,7 @@ type Task interface {
 type Process interface {
 	Pid() uint32
 	Start(context.Context) error
+	Delete() error
 	Kill(context.Context, syscall.Signal) error
 	Wait(context.Context) (uint32, error)
 	CloseStdin(context.Context) error