[notebook] read-only disable element

* remove the drag file to upload text
    * prevent drag binding to show upload form

IPython/frontend/html/notebook/static/js/notebooklist.js

@@ -27,6 +27,8 @@ var IPython = (function (IPython) {
 
 
     NotebookList.prototype.bind_events = function () {
+        if (IPython.read_only)
+        {return}
         var that = this;
         this.element.bind('dragover', function () {
             return false;
@@ -83,6 +85,8 @@ var IPython = (function (IPython) {
             if (!IPython.read_only){
                 // hide delete buttons when readonly
                 this.add_delete_button(item);
+            } else {
+                $('#drag_info').remove();
             }
         };
     };