title: urllib3 - PoolManager.Request - POST - Returns Empty
body: <p>I am having an issue with urlli3. Please see code:</p>
  
  <pre><code>import urllib3
  import certifi
  
  #Setup urllib3 PoolManager
  httpManager = urllib3.PoolManager(cert_reqs='CERT_REQUIRED',ca_certs=certifi.where())
  
  url = 'https://www.kijiji.ca/t-login.html/'
  headers = urllib3.util.make_headers(
      keep_alive=True,
      user_agent='Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.8.1.6) Gecko/20070725 Firefox/2.0.0.6',
      accept_encoding=True
      )
  
  params = {
       'emailOrNickname': 'username',
       'password': 'password',
       'rememberMe': 'true',
       '_rememberMe' : 'on',
       'targetUrl' : 'L15udS9JWHhHMURBNmdjdkFuTFJJeUR3PT0-',
       'submit': 'SignInButton'
       }
  
  f = httpManager.request('POST', url, headers=headers, encode_multipart=False)
  #f = httpManager.request('POST', url, fields=params, headers=headers, encode_multipart=False)
  page = f.data.decode('utf-8')'
  </code></pre>
  
  <p>The return page (f, in code) returns an empty string. Can someone help me debug this please. </p>
  
  <p>The error code I keep getting is 401. Authentication Error. I thought it could be a basic_authentication error but The website says it uses POST method. Could it be that I'm not adding value for the submit button? Do i need to add data for the submit? Coudl you provide details on that?</p>
  
  <p>Thanks,</p>