Fixed cell definition to override ONOS_USER env. var.

Change-Id: If30c5cceac211cf7a38ec474750bd08335ccc77a
diff --git a/utils/warden/bin/cell-def b/utils/warden/bin/cell-def
index 43656ee..badad59 100755
--- a/utils/warden/bin/cell-def
+++ b/utils/warden/bin/cell-def
@@ -12,5 +12,6 @@
     sed -r 's/[ ]+/\=/;s/^/export /'
 
 echo "export OCT=\"10.128.11.1\""
+echo "export ONOS_USER=sdn"
 echo "export ONOS_USE_SSH=true"
 echo "export ONOS_APPS=${apps}"