Travis CI Postgres Upgrade

Saw that this was mentioned in #239. So this is the solution that @lalitkapoor came up with for Goodybag. It's kind of a hack since Postgres has to re-install every time, but it works. Takes longer to run the tests, but hey, at least you get to test against 9.2! Not sure if you want it or not. Feel free to close if you just want to wait on the Travis CI folks.