title: Installing downloaded tar.gz files with pip
body: <p>When I download <code>PyGUI-2.5.4.tar.gz</code> from <a href="http://www.cosc.canterbury.ac.nz/greg.ewing/python_gui/" rel="noreferrer">http://www.cosc.canterbury.ac.nz/greg.ewing/python_gui/</a> and then run</p>
  
  <pre><code>pip install downloads/PyGUI-2.5.4.tar.gz
  </code></pre>
  
  <p>I get a long error, the root of which appears to be the following:</p>
  
  <pre><code>tarfile.ReadError: not a gzip file
  </code></pre>
  
  <p>Any ideas what I'm doing wrong?</p>