title: Date range picker - invalid date
body: <p>I am using this date range picke (<a href="http://www.daterangepicker.com/#options" rel="nofollow">http://www.daterangepicker.com/#options</a>)</p>
  
  <p>Here are some of options, I understand the most but I need help about <strong>"isInvalidDate"</strong></p>
  
  <p>I use this code and it works perfectly. Date 11/12/2015 is disabled and users can't select it.</p>
  
  <pre><code>isInvalidDate: function(date) {
      if (date.format('YYYY-MM-DD') == '2015-11-12') {
          return true; 
      } else {
          return false; 
      }
  },
  </code></pre>
  
  <p>But I need to add few dates to invalid, so user can't use them. 
  I don't know how to do some array and loop through to return true or false days, could anyone help me with this?</p>