Be explicit about out compatibility goals.

Author: theengineear

setup.py

@@ -21,8 +21,9 @@ def readme():
       long_description=readme(),
       classifiers=[
           'Development Status :: 4 - Beta',
+          'Programming Language :: Python :: 2.6',
           'Programming Language :: Python :: 2.7',
-          'Programming Language :: Python :: 3.3',
+          'Programming Language :: Python :: 3',
           'Topic :: Scientific/Engineering :: Visualization',
       ],
       license='MIT',