title: Is EXDATE not included in rrule for Full Calendar
body: <p>I have a recurring calendar event that happens on the 4th Friday of every month and I want to exclude 1 Friday event. I've tried <code>EXDATE</code> but I'm getting an error </p>
  
  <blockquote>
    <p>Failure passing JSON</p>
  </blockquote>
  
  <p>Without <code>EXDATE</code> the rrule works fine.</p>
  
  <p>Here are the details that I'm using in Full Calendar to produce the event</p>
  
  <pre><code>{
      start: "2019-07-06T09:00:00+10:00",
      end: "2019-07-06T15:00:00+10:00",
      rrule: "FREQ=WEEKLY;DTSTART=20190607T090000;EXDATE=20190705T090000;INTERVAL=4;BYDAY=FR",
      title: "Weed Spraying",
      description: "June, Harry, Pat, George, Valda, Helen, Karen, Ken",
      color: "red",
      url: "./?action=detail_view&amp;id=22",
      duration: "06:00"
  }
  </code></pre>