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.
I'm the one that originally changed that.  The reasoning was that in the CI environment we want to ensure that all transactions in the VCR cassette are used.  However in a dev environment, the "you have unused transactions" error masks any real errors and makes it difficult to troubleshoot unless you know about this setting.