Add Ironic scenarios:
* create_and_list_node
* create_and_delete_node
Add Ironic related utils:
* _create_node
* _list_nodes
* _delete_node
Add unit tests for them.
Add Ironic to _Service and BARE_METAL to _ServiceType.
Also there is a new rally-ironic.yaml job file.
Change-Id: I5bfa68d2f9dc30680996d932c5b03b01d6c0a0fa