jupyter: Fix custom.js with capitalize Jupyter

In all examples of custom.js the Jupyter variable is capitalized, but
here it was not. Because of unknown reason, without Jupyter upgrade,
it stopped to working. Switching from "jupyter" to "Jupyter" fixes the
problem.

software/jupyter/buildout.hash.cfg

@@ -36,4 +36,4 @@ md5sum = 33547be93a67530165e079dc3ecfdac3
 
 [custom-js]
 filename = custom.js
-md5sum = 0bf9e2eb1718b14307265fe05a167018
+md5sum = df0149d5b6b58a17270715957db35f82

software/jupyter/custom.js

@@ -81,8 +81,8 @@
  * @static
  */
 
-$([jupyter.events]).on('notebook_loaded.Notebook', function(){
-  var kernelname = jupyter.notebook.kernel_selector.current_selection;
+$([Jupyter.events]).on('notebook_loaded.Notebook', function(){
+  var kernelname = Jupyter.notebook.kernel_selector.current_selection;
   var display_text="<div class='output_subarea output_text output_result'>\
   <pre>Follow these steps to customize your notebook with ERP5 kernel :-</br>\
   1. Make sure you have 'erp5_data_notebook' business template installed in your ERP5</br>\