setup.py: remove download URL, update project URL

The project was moved from googlecode to github.
Because of the move the downloads are now longer available, thus the download_url is invalid.

Although the newest release 0.9 is available on pypi, the download_url makes package managers try to download it from the no longer available URL on googlecode, see #266.

It would be great if you could update the package metadata on pypi and remove the invalid download URL, which would make it possible to install 0.9 from pypi.