fix: Install Nginx before verifying access (#470)
fix: Install Nginx before verifying access (#470)

* fix: Install Nginx before verifying access

Install Nginx before trying to verify that content under the software
root directory can be accessed by nginx.

* fix: Return boolean from _is_nginx_running

open-power-ref-design-toolkit/cluster-genesis,open-power-ref-design-toolkit/cluster-genesis