title: pip freeze not showing packages
body: <p>For example if after installing Tornado with pip like this:</p>
  
  <pre><code>pip install tornado
  Collecting tornado
  ...
  Successfully installed backports-abc certifi singledispatch six tornado
  </code></pre>
  
  <p><code>pip freeze</code> doesn't return tornado package in list, it just shows:</p>
  
  <pre><code>PyMySQL==0.7.2
  </code></pre>
  
  <p>also when I run <code>easy_install</code> it returns:</p>
  
  <pre><code>error: bad install directory or PYTHONPATH
  
  You are attempting to install a package to a directory that is not
  on PYTHONPATH and which Python does not read ".pth" files from.  The
  installation directory you specified (via --install-dir, --prefix, or
  the distutils default setting) was:
  
      /lib/python2.7/site-packages/
  
  and your PYTHONPATH environment variable currently contains:
  
      ''
  </code></pre>
  
  <p>What is going wrong?</p>