title: Item visible in browser not collected by scraper
body: <p>I'm trying to collect data from the SumofUs website; specifically the number of signatures on the petition. The datum is presented like this: <code>&lt;div class="percent"&gt;256,485 &lt;/div&gt;</code> (this is the only item of this class on the Page.)</p>
  
  <p>So I tried this: </p>
  
  <pre><code>import requests
  from bs4 import BeautifulSoup
  
  user_agent = {'User-agent': 'Mozilla/5.0'}
  url = 'http://action.sumofus.org/a/nhs-patient-corporations/'
  
  raw  = requests.get(url, headers = user_agent)
  html = BeautifulSoup(raw.text)
  
  # get the item we're seeking
  number = html.find("div", class_="percent")
  print number
  </code></pre>
  
  <p>It seems that the number isn't rendered (I've tried a couple of user agent strings.) What else could be causing this? How can I work around this in future?</p>