title: Not able to load c3 graph data with ajax
body: <p>HI i want to load dynamic data with date time range with c3 graph 
  Here is my CODE : </p>
  
  <pre><code>$.ajax({
      [...]
      success: function(data) {
          chart.load({
              columns: data,
              unload: chart.columns,
          });
      }
  });
  </code></pre>
  
  <p>The Ajax response is  : </p>
  
  <pre><code>[['Friday', 1],['Friday', 3],['Sunday', 1],['Saturday', 2],['Friday', 3],['Friday', 3],['Friday', 5],['Friday', 3],['Monday', 1],['Friday', 1],['Tuesday', 1]]
  </code></pre>
  
  <p>On success haven't seen anything on my graph . even i have commented "unload"
  but still same  . the function is works fine if i put statically . please help  me </p>