title: different tree view icons and enable/disable checkboxes in jstree
body: <p>I need to change the tree view icons and enable/disable checkboxes<br>
  please view the code below :</p>
  
  <pre><code>function LoadJSTree() {
          $.noConflict();
  
          $(function () {
              $('#demoTree').jstree({
                  'checkbox': {
                      'keep_selected_style': false,
                      'two_state': true
                  },
                  "types": {
                      "#": {
                          "max_children": 1,
                          "max_depth": 4,
                          "valid_children": ["root"]
                      },
                      "root": {
                          "icon": "/static/3.1.1/assets/images/tree_icon.png",
                          "valid_children": ["default"],
                          "check_node": false,
                      },
                      "default": {
                          "valid_children": ["default", "file"],
                          "check_node": true,
                          "uncheck_node": true
                      },
                      "disabled":{
                          "check_node": false,
                          "uncheck_node": false
  
                      },
  
                      "file": {
                          "icon": "glyphicon glyphicon-file",
                          "valid_children": [],
                          "check_node": true,
                          "uncheck_node": true
  
                      }
                  },
  
                  "plugins": ["types"],
                  'core': {
                      'data': [
                          {
                              "text": "Root node", "type": "root", "parent":"#", "children": [
                                    { "text": "Child node 1", "type": "default" },
                                    { "text": "Child node 2", "type": "default" },
                                    { "text": "Child node 3", "type": "default" },
                                    { "text": "Child node 4", "type": "default" },
                                    { "text": "Child node 5", "type": "default" },
                                    { "text": "Child node 6", "type": "default" },
                                    { "text": "Child node 7", "type": "default" },
                                    { "text": "Child node 8", "type": "default" }
                              ]
                          }
                      ],
  
                  },
                  'plugins': ["checkbox"]
              });
  </code></pre>
  
  <p>It doesn't seem to work.</p>
  
  <p>The tree is displayed using same folder icons for every node and check box always present for every node, shouldn't it come disabled for "root" node?
  Could you please let me know what's wrong?</p>