title: flot bar chart xaxis label with rotated text by -90 alignment issue
body: <p>I am using flot library to design stacked bar graph, wherein I am using following js files.</p>
  
  <pre><code>&lt;script src="@Url.Content("~/Scripts/charts/excanvas.js")"&gt;&lt;/script&gt;
  &lt;script src="@Url.Content("~/Scripts/charts/jquery.flot.js")"&gt;&lt;/script&gt;
  &lt;script src="@Url.Content("~/Scripts/charts/jquery.flot.symbol.js")"&gt;&lt;/script&gt;
  </code></pre>
  
  <p>With the following script I am defining my bar chart with rotated text of xaxis label by -90 degree.</p>
  
  <pre><code> $.each(data, function (index, item) {
                  i = (index + 1) * 2;
                  DataValues.push({ data: [i, item.Value], color: Color[i] });
                  DataValues.push([i, item.Value]);
                  TickData.push([i, item.MonthName]);
              });
              $.plot($("#CurrentYearlyTrendsBar"), [{ data: DataValues, color: "#3D69AA" }],
                      {
                          series: { bars: { show: true } },
                          bars: {
                              barWidth: 1.5,
                              align: "center"
                          },
                          xaxis: {
                              ticks: TickData,
                              axisLabelUseCanvas: true,
                              labelAngle: -90,
                          },
                          yaxis: { axisLabelUseCanvas: true },
                          grid: { hoverable: true }
                      });
              $("#CurrentYearlyTrendsBar").UseTooltip();
  </code></pre>
  
  <p>The problem I am having is with positioning of xaxis labels. xaxis labels are positioned to the left edge of respective bar in chart.</p>
  
  <p>Please suggest me how can I center align the xaxis labels to the respective bars.
  Thanks in Advance...</p>