Add python3.6 classifier to setup.py (#763)

Author: dan98765

setup.py

@@ -79,6 +79,7 @@ def run_tests(self):
         'Programming Language :: Python :: 3.3',
         'Programming Language :: Python :: 3.4',
         'Programming Language :: Python :: 3.5',
+        'Programming Language :: Python :: 3.6',
         'Programming Language :: Python :: Implementation :: PyPy',
     ],