Merge pull request #172 from scikit-learn-contrib/issue_171

Fix issue #171

Author: jcrudy

setup.py

@@ -128,7 +128,8 @@ def setup_package():
                         'Topic :: Software Development'],
         'install_requires': [
             'scipy >= 0.16',
-            'scikit-learn >= 0.16'
+            'scikit-learn >= 0.16',
+            'six'
             ],
         'extras_require': {'docs': ['sphinx_gallery'],
                            'dev': ['cython'],