Simplified implementation of renew_slivers as much of this functionality already exists in utils.py.
Simplified implementation of renew_slivers as much of this functionality already exists in utils.py.


Former-commit-id: 99eb05931df45c8f0a57042a8d4511c25267768b
GENI-NSF/gram,GENI-NSF/gram,GENI-NSF/gram