[WAL-3910] Add support for multiple openstack tenant input in offering options.
[WAL-3910] Add support for multiple openstack tenant input in offering options.

opennode/nodeconductor-assembly-waldur,opennode/waldur-mastermind,opennode/waldur-mastermind,opennode/nodeconductor-assembly-waldur,opennode/nodeconductor-assembly-waldur,opennode/waldur-mastermind,opennode/waldur-mastermind