Refactors compute controller setup section in osbash
Refactors compute controller setup section in osbash

This patch refactors some operations in the setup_nova_controller
script to match the install guides and adds link to
install guides.

Change-Id: I7cc662629769cd0ba434fe15acfa2aeb0135ec21

openstack/training-labs,dguitarbite/OpenStack-Labs,openstack/training-labs,dguitarbite/OpenStack-Labs,dguitarbite/OpenStack-Labs,openstack/training-labs