Modernize certs installation plays

* Update the certs installation plays to install and configure the open
  source certs repo using secrets to configure useful settings.
Bugfixes for cert install recipes

* Includes reformating of stage/prod worker playbooks, to eliminate
  inconsistencies that made them difficult to compare.
Enable default CME certs deploy
Merge pull request #19

from Stanford-Online:stv/oss/certs
into Stanford-Online:master