title: Using labels on y axis of flot graph instead of numbers
body: <p>At the moment each <code>team</code> is assigned a value e.g <code>team1.txt == 1</code><br/>
  So when i render the graph each team has a continuous line along the x-axis (timeline).<br/>
  The y-axis has values <code>1 .. 3</code>, how could i change the y-axis' labels?<br/>
  So that instead of seeing <code>1</code> as first metric on y-axis, I saw <code>team1.txt</code> .. then next value on y-axis would be <code>team2.txt</code></p>
  
  <p>html</p>
  
  <pre><code>&lt;div id="content"&gt;
      &lt;div class="demo-container"&gt;
          &lt;div id="placeholder" class="demo-placeholder"&gt;
      &lt;/div&gt;
  &lt;/div&gt;
  &lt;div id="chartLegend"&gt;&lt;/div&gt;
  &lt;/div&gt;
  </code></pre>
  
  <p>javascript</p>
  
  <pre><code>text = '[{"name":"team1.txt","points":[[1389340501000,1],[1389370501000,1],[1389873602000,1],[1390046402000,1],[1390078402000,1]]},{"name":"team2.txt","points":[[1389370501000,2],[1389441601000,2],[1389528002000,2]]},{"name":"team3.txt","points":[[1389370501000,3],[1389441601000,3],[1389441601000,3]]}]';
  var datasets = JSON.parse(text);
  
  var data = [];
  for (var i = 0; i &lt; datasets.length; i++) {
      data.push({label: datasets[i].name, data: datasets[i].points});
  }
  
  
  $.plot($("#placeholder"), data, {
      xaxis: {
          mode: "time",
          min: (new Date(2014, 1, 1)).getTime(),
          max: (new Date()).getTime()
      },
      series: {
          stack: true,
          lines: {
              show: true
          },
          points: {
              show: true
          }
      },
      grid: {
          hoverable: true,
          clickable: true
      },
      legend: {
          noColumns: 5,
          container: $("#chartLegend")
      }
  });
  </code></pre>