schema-version added in VNFD, NSD, VLR, VNFR and NSR

Change-Id: I718533b5fd5dac26d07f2093f42485e56de6adc9
Signed-off-by: garciadeblas <gerardo.garciadeblas@telefonica.com>
diff --git a/models/yang/nsr.yang b/models/yang/nsr.yang
index 12cf850..4f2eb73 100644
--- a/models/yang/nsr.yang
+++ b/models/yang/nsr.yang
@@ -217,6 +217,12 @@
         key "id";
         unique "name";
 
+        leaf schema-version {
+          description "Schema version for the NSR. If unspecified, it assumes v3.0";
+          type string;
+          default "v3.0";
+        }
+
         leaf id {
           description "Identifier for the NSR.";
           type yang:uuid;