Adding app_label to xproto

Change-Id: I0cdc66cd80dfb3bd0ac75aa5dd20330aa3350663
(cherry picked from commit 39d789f9bde6aa4cadcba620f5ff8ea7ea0c5378)
diff --git a/xos/vtr.xproto b/xos/vtr.xproto
index 4ffe085..8628e0f 100644
--- a/xos/vtr.xproto
+++ b/xos/vtr.xproto
@@ -1,4 +1,5 @@
 option kind="vTR";
+option app_label = "vtr";
 option name="vtr";
 
 message VTRTenant (ServiceInstance){