AETHER-3189 Update ids to be dns compliant:

Change-Id: Ic03b51c62fb205a5505a15e743f93b0057f9b93b
diff --git a/config-models/aether-2.0.x/files/yang/onf-connectivity-service.yang b/config-models/aether-2.0.x/files/yang/onf-connectivity-service.yang
index dfc8821..20bda31 100755
--- a/config-models/aether-2.0.x/files/yang/onf-connectivity-service.yang
+++ b/config-models/aether-2.0.x/files/yang/onf-connectivity-service.yang
@@ -7,7 +7,6 @@
   prefix cs;
 
   import ietf-inet-types { prefix inet; }
-  import ietf-yang-types{ prefix yg; }
   import onf-aether-types { prefix at; }
 
   organization "Open Networking Foundation.";
@@ -27,10 +26,8 @@
   }
 
   typedef connectivity-service-id {
-        type yg:yang-identifier {
-            length 1..32;
-        }
-   description "The typedef for connectivity-service-id";
+    type at:aether-identifier;
+    description "The typedef for connectivity-service-id";
   }
 
   container connectivity-services {