Updates DevStack to match Zaqar's API name change

Zaqar is a messaging service which provides support for different
messaging patterns and messaging related semantics.
This fix changes the old API name -queuing- to a more accurate name, -messaging-.

Change-Id: I07ca6ca704a4f07d88c192a5ce1a7c626de1fcea
diff --git a/lib/zaqar b/lib/zaqar
index 43fb5a1..f5e42e3 100644
--- a/lib/zaqar
+++ b/lib/zaqar
@@ -193,7 +193,7 @@
     if [[ "$KEYSTONE_CATALOG_BACKEND" = 'sql' ]]; then
 
         local zaqar_service=$(get_or_create_service "zaqar" \
-            "queuing" "Zaqar Service")
+            "messaging" "Zaqar Service")
         get_or_create_endpoint $zaqar_service \
             "$REGION_NAME" \
             "$ZAQAR_SERVICE_PROTOCOL://$ZAQAR_SERVICE_HOST:$ZAQAR_SERVICE_PORT" \