title: Start a background process upon successful quickstart in cherrypy
body: <p>I have a REST WebService built on top of cherrypy. The service goes online with the <code>cherrypy.quickstart()</code> call.</p>
  
  <p>I want to start a background process with <code>subprocess.Popen()</code> right after the service goes online. The <code>cherrypy.quickstart()</code> call is blocking. How can I add a callback to start the background process?</p>