Fix a bug where the wrong paramter from the /etc/cinder/cinder.conf
file is being used ('transport' -> 'transport_url').
Fix issue around using json instead of yaml for loading the usernames
from the action data from the list_service_usernames action, which uses
single quotes to quote the data, which isn't compatible with json.
Make the testing for the password change in the cinder.conf more robust
by retrying, as juju is essentially async and it's difficult to
determine exactly when the hook will get fired on cinder.
6516a34045