Update .travis.yml
Update .travis.yml

I forgot to add Python 3.2 and 3.3 to the list of versions tested by Travis.  They are now added, so we'll see how that works.  Currently Python 2.5 is failing under a couple of configurations, so I'll run that to ground as well when I have a chance.
HashNuke/stripe-python,NahomAgidew/stripe-python,uploadcare/stripe-python,stripe/stripe-python,Khan/stripe-python,alexmic/stripe-python,zenmeso/stripe-python,woodb/stripe-python,speedplane/stripe-python,koobs/stripe-python