[!] fix #118 add id for source and target

src/controller/tigergraphql/identity.rs

@@ -67,6 +67,10 @@ impl IdentityRecord {
         current
     }
 
+    async fn id(&self) -> String {
+        self.v_id().clone()
+    }
+
     /// UUID of this record.  Generated by us to provide a better
     /// global-uniqueness for future P2P-network data exchange
     /// scenario.