juju status with openstack data omission

[Kapil Thangavelu]

Running status on openstack providers doesn't show machine addresses in status
(unit addresses are shown). This is due to an optimization in status which
relies on provider.get_machines to return ip address information on machines in
an env instead of fetching details per machine. The ostack provider was using
an api which did not provide ip addresses when retrieving multiple servers. The
fix is to out to a listing api that does.