Add python_requires to help pip (#7698)

Author: hugovk

py/setup.py

@@ -32,6 +32,7 @@
     'description': 'Python bindings for Selenium',
     'long_description': open(join(abspath(dirname(__file__)), "README.rst")).read(),
     'url': 'https://github.com/SeleniumHQ/selenium/',
+    'python_requires='>=2.7, !=3.0.*, !=3.1.*, !=3.2.*, !=3.3.*',
     'classifiers': ['Development Status :: 5 - Production/Stable',
                     'Intended Audience :: Developers',
                     'License :: OSI Approved :: Apache Software License',