Add customClass to bar hover hint

Updated the bar mouseover hint to also include the customClass. This
will give developers more control over the color of the hover. Currently
is defaults to a yellow. Now developers can customize the color of the
hover based on the gantt Color passed in to the values.

js/jquery.fn.gantt.js

@@ -947,7 +947,7 @@
                 if (desc) {
                     bar
                       .mouseover(function (e) {
-                          var hint = $('<div class="fn-gantt-hint" />').html(desc);
+                          var hint = $('<div class="fn-gantt-hint" />').addClass(cls).html(desc);
                           $("body").append(hint);
                           hint.css("left", e.pageX);
                           hint.css("top", e.pageY);