title: How to set title to show only month name in Full Calendar
body: <p>How can I set the Full Calendar title to show only month name instead of "month name year name"?</p>
  
  <p><strong>My code:</strong></p>
  
  <pre><code>$('#calendar').fullCalendar({
      header: {
          left: 'prev',
          center: 'title',
          right: 'next'
      },
      titleFormat: {
          month: 'MMMM'                // Tuesday, Sep 8, 2009
      },
      height: 'parent'
  });
  </code></pre>
  
  <p>Using above code is not working and it's showing some js error on console.log</p>
  
  <pre><code>moment.min.js?ver=2.22.2:1 Uncaught TypeError: e.toUpperCase is not a function
  </code></pre>
  
  <p>That message is showing from moment.min.js file. </p>
  
  <p>Is there anything I am wrong?</p>