title: casperjs/slimerjs: get request headers
body: <p>I'm trying to do a crawler using casperjs. Some requests need raw headers edition: I have to get the raw post data, cookies, etc etc, and once I get them, I'd like to modify them (still raw) and do another request with those modified headers. But I can't find a way to do that.</p>
  
  <p>I've found how to retrieve cookies using Phantomjs, but I did not found anything in casperjs/slimerjs documentation.</p>
  
  <p>Thank you for your help</p>