Fix bug 1364253 - Adding contrail-interface-name package to the upgrade list
Adding venv packages to the removal list.
sleep 5 secs between server-manager reimage call, as pxe cannot handle multiple requests.
call setup_vrouter as part of upgrade_Vrouter in case of centos to set proper setting in the qemu.conf

Change-Id: Ibbddf4ea05c218081b5e4aecf7ec98ec544968e1