Modified warden to create borrowed cells on-demand and to scrap returned ones.

Change-Id: If32a0da18ff9d4c05645017e5cc7481bbd1ab0cd
diff --git a/utils/warden/bin/cell-def b/utils/warden/bin/cell-def
index 12fd284..c7c7116 100755
--- a/utils/warden/bin/cell-def
+++ b/utils/warden/bin/cell-def
@@ -8,7 +8,7 @@
 echo "export ONOS_NIC=\"10.128.11.*\""
 
 sudo lxc-ls -F "name,ipv4" --fancy | grep $name | \
-    sed "s/^$name/OC/" | tr "[:lower:]" "[:upper:]" | \
+    sed "s/^$name-/OC/" | tr "[:lower:]" "[:upper:]" | \
     sed -r 's/[ ]+/\=/;s/^/export /'
 
 echo "export OCT=\"\$OC1\""