Replace oslo_utils.timeutils.isotime

The function 'oslo_utils.timeutils.isotime()' is deprecated in
version '1.6' and will be removed in a future version.
We are using datetime.datetime.isoformat() instead.
For more information: http://docs.openstack.org/developer/oslo.utils/api/timeutils.html#oslo_utils.timeutils.isotime

Change-Id: I7d41e33bc42f8eb354c8a659123bf34e077a9626
Closes-Bug: #1514331
1 file changed