Add Marconi to Tempest config

This patch adds queuing to tempest config, provided queuing is
available in devstack.

Change-Id: I2925a07d312c1f8ab2fe465f74f0bef9299eef40
Implements: blueprint add-basic-marconi-tests
Merge "Add Marconi to Tempest config"
Merge branch 'master' of github.com:openstack-dev/devstack