title: change slotDuration of fullCalendar
body: <p>I'm using ui-calendar (witch is based on fullCalendar), and default slot duration = '00:30:00'. I want change it to '00:15:00'.</p>
  
  <p>My config object:</p>
  
  <pre><code>  /* config object */
    $scope.uiConfig = {
      calendar:{
        height: 450,
        editable: true,
        duration: '00:15:00',
        slotDuration: '00:15:00',
        header:{
          left: 'title',
          center: '',
          right: 'today prev,next'
        },
        eventClick: $scope.alertOnEventClick,
        eventDrop: $scope.alertOnDrop,
        eventResize: $scope.alertOnResize
      }
    };
  </code></pre>
  
  <p>According to <a href="http://fullcalendar.io/docs/agenda/slotDuration/" rel="nofollow">http://fullcalendar.io/docs/agenda/slotDuration/</a>.
  But this doesn't help :(</p>