Bumping versions

Checklist:

Run the unit tests
Run the Twilio stage integration tests
Add a short change description to CHANGES
Update the version number in twilio/__init__.py
Update the version number in docs/conf.py
Commit the version bumps.

Tag a new release in Github with both the version and the latest tag.

  git tag 3.3.9
  git tag -d latest
  git tag latest
  git push upstream --tags

Upload to PyPI. You need a ~/.pypirc file with this in it:
```
  [pypirc]
  servers =
      pypi

  [server-login]
  username:<username>
  password:<password>
```
You can get the username and password from someone who has them.

Then run:
```
  python setup.py sdist
```
If you are satisfied with the output, upload to PyPI:
```
  python setup.py sdist upload
```