Updated openstack/openstack
Project: openstack/cinder  e488d78ea170cbda662c540cea31fec47716ad46

Convert the DateTime into ISO8601 format for Ceilometer

The fields of DateTime type should be converted to the time in
ISO8601 format, when they are put in the usage information to be
reported to Ceilometer.

Change-Id: I67e9e3609291d0d835156dfd9cfda88deae119c1
closes-bug: #1372791