[COOK-3685] Upgrade Repo Attributes for Postgresql 9.3

- Adds pgdg yum repo attributes for rhel based systems for 9.3
- Enhances pgdg yum repo attributes for newer 9.2 packages

Further information can be found here:  http://yum.postgresql.org/repopackages.php#pg93

Signed-off-by: Seth Vargo <sethvargo@gmail.com>