Vagrantfile/VM for PG JDBC Driver Testing

Hi-

To simplify testing of the PG JDBC driver I created a Vagrant config
that spins up a VM with 5 PG installations (versions 8.4, 9.0, 9.1,
9.2, and 9.3) and creates the users/databases needed for running the
JDBC driver tests (including all the SSL tests). All five PG servers
are running in the same VM (separate installations in single Ubuntu
12.04 VM).

I created this so that I could more easily run the JDBC driver tests
and in particular write new tests for the new SSL factory patch
submitted a couple weeks back. I haven't completed the new tests yet
but I figured I'd share this now as it's useful on it's own.

I think it'd be good to have this (or something similar) merged into
the JDBC driver's repo itself as it makes it *much* easier for someone
to test out a change (particularly against multiple version of PG).
Double so for someone new trying to get started.

Let me know what you guys think.

GitHub repo: https://github.com/jackdb/pgjdbc-test-vm

Thanks,
Sehrope Sarkuni