This drives https://jenkins.opendaylight.org/releng/view/netconf/job/netconf-csit-1node-scale-max-devices-only-aluminium/ and does a lot of ineffecient things:

• the devices should be setup with a single REST request
• the devices should be torn down with a single REST request
• checking for device tear-down should operate on 'all devices' torn down

If it's not possible to setup or tear down with a single request, it should be done using parallel threads.