title: Using python_requires to require Python 2.7 or 3.2+
body: <p>How do I use <code>python_requires</code> classifier in setup.py to require Python 2.7.* or 3.2+?</p>
  
  <p>I have tried many configurations, including this one: <code>~=2.7,==3,!=3.0,!=3.1,&lt;4</code> but none have worked</p>