CORD-2281: Associate EPC service instance objects with sites

Change-Id: If8f087817e2ca8bf34434f05424709a0cc8a26cd
diff --git a/xos/vepc.xproto b/xos/vepc.xproto
index 3a23d6b..6ad6f96 100644
--- a/xos/vepc.xproto
+++ b/xos/vepc.xproto
@@ -11,5 +11,6 @@
     option name = "VEPCServiceInstance";
     option verbose_name = "Virtual Evolved Packet Core ServiceInstance";
     optional string description = 1 [help_text = "service chain details", max_length = 128, null = True, db_index = False, blank = True];
-    required string blueprint = 3 [help_text = "Select the service graph blueprint", db_index = False, default = 1, choices = "(('build', 'CORD Build'),)"];
+    required manytoone site->Site:+ = 2 [help_text = "Site of the EPC Service", null = False, db_index = True, blank = False];
+    required string blueprint = 3 [help_text = "Select the service graph blueprint", db_index = False, default = 1, choices = "(('build', 'MCORD 4.1'),)"];
 }