Speed-up and/or reduce re-deployment playbook

[Apreche]

The deployment playbook currently contains the entire process for setting up the new instance from almost scratch. This makes sense for the initial release of the new project. However, for further releases, much of this process becomes unnecessary to repeat. There is no need to re-install PostgreSQL every single release.

Even though Ansible will check that it is installed and skip those steps, it may still be beneficial to skip some steps completely. Maybe we can figure out a way to run a different, smaller, playbook for the first release vs. every subsequent release.

There may also be ways to use Ansible caching and other features to dramatically speed up the release process.