Make tweepy compatible with Python 3.3

Major points are (as far as I can remember):
* Updated dependencies to more recent versions.
* Moved testing to tox.
* Passing test_api and test_utils tests (other tests *probably* failing - I can look at them if you'd like - I notice some are failing under Python 2 anyway).
* Calls to bound endpoints are no longer passing in self - this was causing self to be passed in as an http param.
This was a fix to a problem I had with testupdateprofilebannerimage. I couldn't see any good reason why self was being passed in, and it was causing an extra parameter to be passed to the http call.