Update setup.py to drop python 2.6, 3.2, and 3.3

Since those versions are no longer being tested via travis, best to not
indicate that they are supported.

Author: agschwender

setup.py

@@ -27,11 +27,9 @@ def run(self):
       classifiers=[
         'License :: OSI Approved :: Apache Software License',
         'Programming Language :: Python :: 2',
-        'Programming Language :: Python :: 2.6',
         'Programming Language :: Python :: 2.7',
         'Programming Language :: Python :: 3',
-        'Programming Language :: Python :: 3.2',
-        'Programming Language :: Python :: 3.3',
+        'Programming Language :: Python :: 3.6',
         ],
       url='https://github.com/agschwender/pilbox',
       author='Adam Gschwender',