Add major.minor classifiers

https://github.com/httplib2/httplib2/pull/77
diff --git a/setup.py b/setup.py
index 49eb6b1..b779d1f 100755
--- a/setup.py
+++ b/setup.py
@@ -67,7 +67,12 @@
         'Operating System :: OS Independent',
         'Programming Language :: Python',
         'Programming Language :: Python :: 2',
+        'Programming Language :: Python :: 2.7',
         'Programming Language :: Python :: 3',
+        'Programming Language :: Python :: 3.3',
+        'Programming Language :: Python :: 3.4',
+        'Programming Language :: Python :: 3.5',
+        'Programming Language :: Python :: 3.6',
         'Topic :: Internet :: WWW/HTTP',
         'Topic :: Software Development :: Libraries',
     ),