Modernize certs installation plays

* Update the certs installation plays to install and configure the open
  source certs repo using secrets to configure useful settings.

These are the play adaptaptions I developed doing a lot of failed installs. They seem to work well for me.

This doesn't include a stanza in one of the host playbooks, because I think we're not certain where this bleongs?

@stvstnfrd @jbau