title: ivh-treeview disable the checkbox for the first node
body: <p>I am using the <code>IVHTREEVIEW</code> in one of our application. Our tree-view is something like below:</p>
  
  <pre><code>+ click + to see all items in list
  Item
  Item1.1
  Item2
  Item2.2
  </code></pre>
  
  <p>We display the checkbox for each item. For the enduser a checkbox for the first node 'Click + to see all Items in list' doesn't make sense in our business. I need to disable or hide the <code>CHECKBOX</code> only for that node( 'Click + to see all Items in list'). How can I do this?</p>
  
  <p>I tried to use 'useCheckboxes' and set it to false, in the below function of ivh-treeview.js. But it is not working. </p>
  
  <p>Can you tell me how we can achieve this?</p>
  
  <pre><code>trvw.label = function(node) {
  trvw.label = function(node) { if(node[localOpts.labelAttribute] == "Click + to see all Items in list"){
  node[localOpts.useCheckboxes] = false; } return node[localOpts.labelAttribute];};
  </code></pre>