Add additional trove classifiers to setup.py

- General Python support, Python 2 support, Python 3 support
- CPython support (to contrast with PyPy)
diff --git a/setup.py b/setup.py
index f4e9e18..e93e791 100644
--- a/setup.py
+++ b/setup.py
@@ -57,13 +57,17 @@
 
         'License :: OSI Approved :: MIT License',
 
+        'Programming Language :: Python',
+        '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 :: 3.4',
         'Programming Language :: Python :: 3.5',
         'Programming Language :: Python :: 3.6',
+        'Programming Language :: Python :: Implementation :: CPython',
         'Programming Language :: Python :: Implementation :: PyPy',
 
         'Topic :: Security :: Cryptography',