Cleanup client not found errors.

And fix remove calls to return a notFound error

Signed-off-by: Daniel Nephin <dnephin@docker.com>

client/secret_remove.go

@@ -9,5 +9,5 @@ func (cli *Client) SecretRemove(ctx context.Context, id string) error {
 	}
 	resp, err := cli.delete(ctx, "/secrets/"+id, nil, nil)
 	ensureReaderClosed(resp)
-	return err
+	return wrapResponseError(err, resp, "secret", id)
 }