Resolve "randomize webwork tasks"

Closes #72 (closed)

layouts/shortcodes/webwork.html

-
 <iframe
+  id="webwork"
   class="embed-responsive-item"
   style="border-width: 0"
   src="{{ index .Params 0 }}"
   width="100%"
 >
-</iframe><script>iFrameResize({log:true,inPageLinks:true,resizeFrom:'child'})</script>
\ No newline at end of file
+</iframe><script>
+iFrameResize({log:true,inPageLinks:true,resizeFrom:'child'})</script>
+
+<script>
+  let mysrc = document.getElementById('webwork').src;
+  let newsrc = mysrc.replace(/Seed=[0-9]+/g,"Seed="+Math.floor(Math.random()*10000000));
+  document.getElementById('webwork').src = newsrc;
+</script>