title: PyQt Class not working for the second usage
body: <p>I'm using PyQt to fully load a page(including JS) and get it contents using Beautiful Soup. Works fine at the first iteration, but after, it crashes. I don't have a big knowledge in Python, and even less in PyQt, so any help is very welcome. </p>
  
  <p>Class borrowed from <a href="https://stackoverflow.com/questions/14776989/javascript-interpreter-only-being-executed-on-the-first-page">here</a>.</p>
  
  <pre><code>from PyQt4.QtCore import QUrl, SIGNAL
  from PyQt4.QtGui import QApplication
  from PyQt4.QtWebKit import QWebPage
  
  from bs4 import BeautifulSoup
  from bs4.dammit import UnicodeDammit
  import sys
  import signal
  
  
  class Render(QWebPage):
      def __init__(self, url):
          self.app = QApplication(sys.argv)
          QWebPage.__init__(self)
          self.html = None
          signal.signal(signal.SIGINT, signal.SIG_DFL)
          self.connect(self, SIGNAL('loadFinished(bool)'), self._finished_loading)
          self.mainFrame().load(QUrl(url))
          self.app.exec_()
  
      def _finished_loading(self, result):
          self.html = self.mainFrame().toHtml()
          self.soup = BeautifulSoup(UnicodeDammit(self.html).unicode_markup)
          self.app.quit() 
  
  ###################################################################
  
  
  l = ["http://www.google.com/?q=a", "http://www.google.com/?q=b", "http://www.google.com/?q=c"]
  
  for page in l:
      soup = Render(page).soup
      print("# soup done: " + page)
  </code></pre>
  
  <p><img src="https://i.stack.imgur.com/uyXDy.jpg" alt="enter image description here"></p>