Remove unused event

This event never seems to get used.

IPython/html/static/base/js/contentmanager.js

@@ -114,7 +114,6 b' define(['
             success : $.proxy(that.rename_success, that),
             error : $.proxy(that.rename_error, that)
         };
-        this.events.trigger('rename_notebook.Notebook', data);
         var url = utils.url_join_encode(
             that.base_url,
             'api/notebooks',