Move from distutils to setuptools
Moves gravatar package into src/ directory
Moves tests out of the package
Update copyright year
Rename package from gravatar to django_gravatar
Removes models.py and chmod -x __init__.py
Rename gravatar_tags.py -> gravatar.py
Rewrite with support for modern Python & Django

Adds some new features, better separation between utilities and template tags,
a better testsuite, more documentation, and much more.