refer to notebooks, not kernels.

IPython/html/templates/tree.html

@@ -77,7 +77,7 b' data-base-kernel-url="{{base_kernel_url}}"'
 
         <div id="running_list">
             <div id="running_list_header" class="row-fluid list_header" style='display:none'> 
-                <div> There are no running kernels </div>
+                <div> There are no notebooks running. </div>
             <!-- damn it, I seem to need this stupid placeholder, otherwise items don't get added to the list -->
             </div> 
         </div>