(pdb-775) Retire old postgres versions

This PR retires support for all postgres versions less than 9.3,
which means we are no longer deprecating any databases. This PR
keeps around the old deprecation logic for future use and updates the
versions we do not support to include all postgres versions <9.3. This
PR also updates our acceptance test helpers to install postgres from
the upstream packages on the postgres site so that our tests always use
9.3.
There's not really anything to it, I'd say just go ahead and remove it