title: Fullcalendar background-image for fc-sun
body: <p>I set background-image for sunday in month view, but also the day "Sunday" in header is set with same background, while others header days is set correctly. I see that css for table thread have .fc-sun .fc-mon etc. too, but I don't kwow how remove these class from thread. How can I solve this problem ?</p>
  
  <p>I have this in my fullcalendar.css :</p>
  
  <pre><code>.fc-widget-header{
  background-color: #900;
  }
  
  .fc-sun {
    background-image:url('../img/myImage.png');
    background-repeat:repeat-x;
    background-repeat:repeat-y;
  }
  </code></pre>