cleanup & refactor

Cleanup all the things. Major changes include:

*  <code>databases::postgresql</code> hates the way we install pg93, so hack around it
*  use yum_repository
*  use encrypted data bags
For the <code>database</code> resource. Normally <code>include_recipe "database::#{type}"</code> covers it, but it breaks on the <code>pgdg</code> repo.