Add YANG gui apps to simon-single cell.

Change-Id: Iaa142ff9123783caa1c7da13649caa9dafd3a3f0
diff --git a/tools/test/cells/simon-single b/tools/test/cells/simon-single
index 1011419..c15a0a1 100644
--- a/tools/test/cells/simon-single
+++ b/tools/test/cells/simon-single
@@ -4,4 +4,4 @@
 export OC1="192.168.56.1"
 export OCN="192.168.56.99"
 
-export ONOS_APPS="drivers,openflow,fwd,null,cord-support"
+export ONOS_APPS="drivers,openflow,fwd,null,yang-gui,models.demo"