Deprecate Python 2.6, Remove All But One Driver

Per a [recent discussion](https://groups.google.com/a/pyfarm.net/d/msg/discuss/N1y5ZqwY8Dc/mIJPnZodFEEJ) this change removes direct testing for Python 2.6 and add Python 3.4 to the list of Python versions to test.  We're also removing all but one driver per database too.  We were initially testing multiple drivers to ensure that if someone tried using another driver there would not be any obvious problems out of the box.