update to latest yang-js/yang-express and adapt schema/server to conform to latest interface changes
diff --git a/schema/xos-core.yang b/schema/xos-core.yang
index 3de5ba3..846da5c 100644
--- a/schema/xos-core.yang
+++ b/schema/xos-core.yang
@@ -75,7 +75,7 @@
       mandatory true;
     }
 
-    list subscribed-tenants {
+    list subscribed-tenant {
       config false;
       // not exactly clear how this is populated
     }