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 really don't think this is the right thing to do.

If you get "you have unused transactions" in the dev environment, it probably means that you've changed the code in such a way as to require the rerecording of the cassettes. In that case, you don't need to know about the setting, you just need to remove the local cassettes so they'll be rerecorded - then you can just continue testing. If you make a pr without rerecording the cassettes, Travis will fail, forcing you to rerecord them anyway.

If you want to ensure that all the transactions are used in the CI environment, then you should ensure that that they're all used in the dev environment as well.