Add Highlight Tool to the CornerstoneDemo

[cancan101]

trafficstars

The highlight tool is available at: https://github.com/chafey/cornerstoneTools/blob/master/examples/allImageTools/index.html but not in the cornerstoneDemo. Should be easy to add using:

<button id="highlight" type="button" class="btn btn-sm btn-default" data-container='body' data-toggle="tooltip" data-placement="bottom" title="Highlight"><span class="fa fa-pencil-square-o"></span></button>

            $(buttons[12]).on('click touchstart',function() {
              disableAllTools();
              cornerstoneTools.highlight.activate(element, 1);
            });