OpenStack - Ensure inventory is collected for all tenants.

@Fryguy @blomquisg please review.

For OpenStack refresh, ensure inventory is collected for all of the
tenants the EMS can access.

Extended OpenstackHandle to include tenant iterators.
Updated EmsOpenstack and the openstack parser to use the OpenstackHandle accordingly.
Updated spec tests and rerecorded vcr cassettes.
Yeah, floating ips.  In the openstack parser in ems_refresh we let the `@network_service` be either nova or neutron and ask for addresses.  In this PR, the openstack parser calls `@network_service.addresses_for_accessable_tenants`, which should break when the network service is really neutron.

I thought one of the test envs had neutron configured...