title: fullCalendar hide event titles, but set cell/day background
body: <p>Using: </p>
  
  <pre><code>* FullCalendar 2.1.1
  * month view
  </code></pre>
  
  <p>I would like to display a mini calendar - all it shows is the day of the month - no event titles. 
  But, on days that have events - i would like that cell to have a background color. (Sample below)</p>
  
  <p>I guess via CSS i can manually hide all events using <code>.fc-event-container {display: none;}</code>
  but what code would i use to change the cell background, if an event exists? something for <code>dayRender</code>? </p>
  
  <p>Thanks</p>
  
  <p><img src="https://i.stack.imgur.com/bI2X5.jpg" alt="enter image description here"></p>