Revert "Revert "Merge pull request #493 from opscode/pdb/11.1_dbUnixUser""

This reverts commit 147f691d2af4da5aa486e96c50f680480e28e786 and reinstates the
changes from PR #493
Fix typo on include_recipe
Merge pull request #573 from opscode/pdb/11.1_dbUnixUser.2

Remove hardcoded postgres-user references