Pgdg repositories improvements

https://tickets.opscode.com/browse/COOK-3717

I made the following changes:

* Support apt.postgresql.org version specific packages.
  This change will also allow the user to install RC and BETA
  version of posrgres.

* Test PGDG repositories with PostgreSQL version 9.3
  Bump the version to 9.3 in testing environment

* Add debian-7.1.0 platform to testing environment

* Update PGDG yum repository data and add version 9.3

* Don't rely on meta-packages to install the right packages version on Debian/Ubuntu