List Python 2 and 3 support in setup.py

zc.recipe.egg_/setup.py

@@ -52,6 +52,8 @@ setup(
        'Framework :: Buildout',
        'Intended Audience :: Developers',
        'License :: OSI Approved :: Zope Public License',
+       'Programming Language :: Python',
+       'Programming Language :: Python :: 3',
        'Topic :: Software Development :: Build Tools',
        'Topic :: Software Development :: Libraries :: Python Modules',
        ],