title: Can't call strftime on numpy.datetime64, no definition
body: <p>I have a datetime64 <code>t</code> that I'd like to represent as a string.</p>
  
  <p>When I call strftime like this <code>t.strftime('%Y.%m.%d')</code> I get this error:</p>
  
  <pre><code>AttributeError: 'numpy.datetime64' object has no attribute 'strftime'
  </code></pre>
  
  <p>What am I missing? I am using Python 3.4.2 and Numpy 1.9.1</p>