migrate to upstream libcompose in one and a half go

vendor/github.com/docker/distribution/manifest/versioned.go

@@ -0,0 +1,9 @@
+package manifest
+
+// Versioned provides a struct with just the manifest schemaVersion. Incoming
+// content with unknown schema version can be decoded against this struct to
+// check the version.
+type Versioned struct {
+	// SchemaVersion is the image manifest schema that this image follows
+	SchemaVersion int `json:"schemaVersion"`
+}