Python 3 deprecated the logger.warn method in favor of warning
Python 3 deprecated the logger.warn method in favor of warning

Python 3 deprecated the logger.warn method. See:
https://docs.python.org/3/library/logging.html#logging.warning, so we
prefer to use warning instead.

Change-Id: If714af9fe0c5577e19be38dc6cbf1f1f76db4db4

openstack/barbican,openstack/barbican