Bump libcompose and its dependencies

vendor/github.com/docker/engine-api/client/image_save.go

@@ -0,0 +1,22 @@
+package client
+
+import (
+	"io"
+	"net/url"
+
+	"golang.org/x/net/context"
+)
+
+// ImageSave retrieves one or more images from the docker host as an io.ReadCloser.
+// It's up to the caller to store the images and close the stream.
+func (cli *Client) ImageSave(ctx context.Context, imageIDs []string) (io.ReadCloser, error) {
+	query := url.Values{
+		"names": imageIDs,
+	}
+
+	resp, err := cli.get(ctx, "/images/get", query, nil)
+	if err != nil {
+		return nil, err
+	}
+	return resp.body, nil
+}