title: Fullcalendar Scheduler resource refetch not updating vertical resource view
body: <p>I have a problem with updating resources using fullcalendar scheduler plugin.
  I use a vertical resource view. Oddly enough this problem does not happen in timeline view.   </p>
  
  <p>I use a function to (re)fetch resources, let's say it's something simple, for purposes of an example, as:  </p>
  
  <pre><code>var t = this;
  t.someParam = false;
  $(el).fullCalendar({
      resources: function(callback){
              //do stuff
              if(t.someParam === true){
                  callback([{id: 1, title: 'title'}]);
              }
              else{
                  callback([{id: 2, title: 'title2'}]);
              }
          }
      }
  );
  </code></pre>
  
  <p>This means when i do a refetch, i call</p>
  
  <pre><code>$(el).fullCalendar('refetchResources')
  </code></pre>
  
  <p>The fetch works (resources callback is called). Also, before the refetch, i set a parameter (e.g "someParam") to some value ( true), which affects the results (see example), just to simulate differing results. The results are a working array and if i call</p>
  
  <pre><code>$(el).fullCalendar('getResources') //after refetch
  </code></pre>
  
  <p>the intended resources have been added to the calendar.<br>
  The problem is, the resources will not render in the view, until i skip to another view or change the date. I tried 'render' function, but this doesn't work. I would not want to use 'addResource' (preferably), even though this would render the view immediately.I would want the view to update , like it would with 'refetchEvents'. </p>