vendor.conf: pin branches to releases or commits

Most of the dependencies have been copied from libpod's vendor.conf
where such a cleanup has been executed recently.

Signed-off-by: Valentin Rothberg <rothberg@redhat.com>

vendor/github.com/docker/distribution/registry/api/errcode/handler.go

@@ -36,5 +36,9 @@ func ServeJSON(w http.ResponseWriter, err error) error {
 
 	w.WriteHeader(sc)
 
-	return json.NewEncoder(w).Encode(err)
+	if err := json.NewEncoder(w).Encode(err); err != nil {
+		return err
+	}
+
+	return nil
 }

vendor/github.com/docker/distribution/registry/api/v2/routes.go

@@ -14,6 +14,15 @@ const (
 	RouteNameCatalog         = "catalog"
 )
 
+var allEndpoints = []string{
+	RouteNameManifest,
+	RouteNameCatalog,
+	RouteNameTags,
+	RouteNameBlob,
+	RouteNameBlobUpload,
+	RouteNameBlobUploadChunk,
+}
+
 // Router builds a gorilla router with named routes for the various API
 // methods. This can be used directly by both server implementations and
 // clients.