title: Multiple backend call with Retrofit at same time
body: <p>I' using Retorfit for one my Android project and I just realized this cool library, doesn`t make any call in parallel, but once by one. I always staring a new Thread or an AsyncTaks for my backend calls (obviously), but Retrofit put all of my request into a Queue (I think) and processing them after each other. </p>
  
  <p>Re-implement the backend side is not a solution for now, does anyone know how can I force retrofit to take 3-4 request at the same time ? </p>
  
  <p>Thank you,</p>