title: android picasso library add token header
body: <p>I have been breaking my brain on this one,</p>
  
  <p>I am using Picasso library to load and download images from my server, but now I want to add a header in my download request and I cant seem to find a way of doing it. all i want to do is set a header like : 
  setHeader("Authorization", "Bearer " + token);</p>
  
  <p>I use this header in any of my server requests, but cant find a way to add it to the picasso line.</p>
  
  <p>Any help would be appreciated, Thanks!</p>