Fix version number to upload to PyPI

This should fix the `pip install` problem of the PyPI package as described on [StackOverflow](http://stackoverflow.com/questions/26819350/pip-not-getting-current-version/). After merging this PR you'd have to:

1. Delete the not-working 1.4 package from PyPi (manually in the web interface), and
1. Run `./setup.py sdist upload` (after authenticating via `./setup.py register` beforehand, naturally)

I've done this for you already (to test that it works, really), and `pip install django-todo` now works fine.