title: how to convert a string datetime with unknown timezone to timestamp in python
body: <p>I have a datetime like this <code>Thu Jun 02 11:56:53 CDT 2011</code>
  I tried to convert it to datetime object using the code below</p>
  
  <pre><code>from dateutil import parser
  timestamp = parser.parse("Thu Jun 02 11:56:53 CDT 2011")
  </code></pre>
  
  <p>But I get this warning</p>
  
  <pre><code>UnknownTimezoneWarning: tzname CDT identified but not understood. 
  Pass `tzinfos` argument in order to correctly return a timezone-aware datetime.
  In a future version, this raise an exception.
  category=UnknownTimezoneWarning)
  </code></pre>
  
  <p>There is no warning when I use <code>UTC</code> instead of <code>CDT</code>. 
  Can I use <code>tzinfos</code> to fix this ?</p>