list recommended version of PostgreSQL
What does this MR do?
List recommended version of PostgreSQL per https://about.gitlab.com/2017/03/22/gitlab-9-0-released/#omnibus-gitlab-package-improvements-ce-ee
List recommended version of PostgreSQL per https://about.gitlab.com/2017/03/22/gitlab-9-0-released/#omnibus-gitlab-package-improvements-ce-ee