labs: reorder setup_neutron_controller.sh
labs: reorder setup_neutron_controller.sh

Reorder content of setup_neutron_controller.sh to match the
install-guide. Add comments, tweak echo statements.

Change-Id: Ib2b7518244e3deaac06ace55f9ca779040ad4c3f

Nabs007/training-guides,Nabs007/training-guides,Nabs007/training-guides,harrisonfeng/training-guides,openstack/training-guides,harrisonfeng/training-guides,harrisonfeng/training-guides,openstack/training-guides