title: prevent an external event to be dropped on full calendar if earlier than today's date
body: <p>I am using the fullcalendar jquery plugin to create a schedule of events.  I want to prevent the user from dropping an external event on the calendar if it is earlier than current date.
  This is my current code:</p>
  
  <pre><code>$('#edit_calendar').fullCalendar({
      header:
      {
          left: 'prev,next today',
          center: 'title',
          right: 'month,agendaWeek,agendaDay'
      },
      titleFormat: { month: 'MMMM' },
      defaultView: 'month',
      droppable: true,
          drop: function (date, jsEvent, ui, resourceId) {
              //compare today's date with drop date - if in the past, don't allow
              var today = moment().startOf('day');
              var dropDate = moment(date).startOf('day');
              if (dropDate &lt; today)
              {
                  //The alert is shown
                  alert("An event in the past cannot be added, updated, or deleted.");
                  return false;
              }
              else
              {              
                  var memberName = $(this).data('event').title;
                  var memberID = $(this).attr('id').toString();          
                  //Create Event - add to array
                  var newEvent = new Object();
                  newEvent = {
                      title: memberName,
                      id: memberID,
                      start: date.format(),
                      end: date.format(),
                      objectID: 0
                  };
                  eventsAdded.push(newEvent);
              }
          },
          ...rest of code
  </code></pre>
  
  <p>If the event is dropped before the current day display the alert and do not create the event.  If shown after the current day, create the event.</p>
  
  <p>In the code above, the alert is shown, but the event is still created.  If the event is dropped after the current day, the event is created.</p>
  
  <p>I thought by adding <code>return false</code> after the alert is displayed it will prevent the event from being created.  However, the alert is shown AND the event is created.</p>
  
  <p>Do I have to remove the event or is there a way to prevent the event from being created?</p>