title: Add a background image to a connector in jsPlumb
body: <p>I'm wondering if it is possible to add a background image to a connector.</p>
  
  <p>My objective is to create something like this:
  <img src="https://i.stack.imgur.com/57t7d.png" alt="enter image description here"></p>
  
  <p>This way I could have an animated images in the background symbolizing the direction and type of the connection.</p>