add python version classifiers

setup.py

@@ -115,6 +115,10 @@ setup(
         'Operating System :: MacOS :: MacOS X',
         'Operating System :: POSIX :: Linux',
         'Programming Language :: Python',
+        'Programming Language :: Python :: 3',
+        'Programming Language :: Python :: 3.2',
+        'Programming Language :: Python :: 3.3',
+        'Programming Language :: Python :: 3.4',
         'Topic :: Security :: Cryptography',
         'Topic :: System :: Archiving :: Backup',
     ],