reduce our postgresql version from 9.3 to 9.2

* I had planned to upgrade us from 9.2 to 9.3 over the Christmas break,
  but I had a baby instead so production is still 9.2
* I'm thinking we might just stay on 9.2 until next Christmas when we
  can go to 9.4. Upgrading involves taking the site offline so I'm
  reluctant to do it when we have significant traffic. Also, 9.3 doesn't
  have any urgent features we need