Use typeurl package for spec types

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

runtime/runtime.go

@@ -17,7 +17,7 @@ type IO struct {
 
 type CreateOpts struct {
 	// Spec is the OCI runtime spec
-	Spec []byte
+	Spec *types.Any
 	// Rootfs mounts to perform to gain access to the container's filesystem
 	Rootfs []mount.Mount
 	// IO for the container's main process

runtime/task.go

@@ -10,7 +10,6 @@ type TaskInfo struct {
 	ID          string
 	ContainerID string
 	Runtime     string
-	Spec        []byte
 	Namespace   string
 }