title: python requests gives 'None' response, where json data is expected
body: <p>Firstly, I should add that you can find this request by doing the following:</p>
  
  <pre><code>1- Go to [airline site][1]
  2- Type in "From" = "syd"
  3- Type in "To" = "sin"
  4- Make the departure date sep.3 and click one-way and search
  5- On the search result page check your network get request when you click on an available seat option radio button
  </code></pre>
  
  <p>I'm trying to use the requests module to get the response for example from <a href="http://www.singaporeair.com/chooseFlightJson.form?tripType=O&amp;selectedFlightIdDetails[0]=0%7CFF31SYD&amp;hid_recommIDs=&amp;userPreferedCurrency=&amp;hid_flightIDs=" rel="nofollow">this site</a></p>
  
  <p>And this is what I'm trying:</p>
  
  <pre><code>url = "http://www.singaporeair.com/chooseFlightJson.form?"
  payload = {'selectedFlightIdDetails[0]':amount_data,'hid_flightIDs':'','hid_recommIDs':'','tripType':"O",'userPreferedCurrency':""}
  
  response = requests.get(url, params=payload)
  print response.json()
  </code></pre>
  
  <p>The response is supposed to be:</p>
  
  <pre><code>{"price":{"total":"595.34","currency":{"code":"AUD","label":""},"adult":{"count":1,"label":"Adult","cost":"328.00","total":"328.00"},"child":{"count":0,"label":"Child","cost":"0.00","total":"0.00"},"infant":{"count":0,"label":"Infant","cost":"0.00","total":"0.00"},"addOns":[{"label":"Airport / Government taxes ","cost":"83.24"},{"label":"Carrier Surcharges","cost":"184.10"}],"disclaimer":"Prices are shown in Canadian Dollar(CAD)","rate":"595.34 AUD \u003d 913.80 CAD","ratehint":"Estimated","unFormattedTotal":"595.34"},"messages":{"O3FF11SYD":"A few seats left","O1FF31SYD":" ","R0FF31SYD":"A few seats left","O2FF31SYD":"A few seats left","O0FF31SYD":" ","O1FF11SYD":"A few seats left","O0FF21SYD":" ","O2FF21SYD":" ","O3FF21SYD":" ","O1FF21SYD":" "},"cabinClass":{"onwardCabin":["Economy"]}} 
  </code></pre>