Replace keystone client usage w/ openstack client
Replace keystone client usage w/ openstack client

With the most recent keystoneclient releases, the `keystone` client is
removed in favor of the `openstack` client. Change this check as such.

aacole/ursula-monitoring,blueboxgroup/ursula-monitoring,blueboxgroup/ursula-monitoring,blueboxgroup/ursula-monitoring,blueboxgroup/ursula-monitoring,aacole/ursula-monitoring,aacole/ursula-monitoring,aacole/ursula-monitoring