fix help-links on Firefox

link text must come after icon to layout properly on Firefox

this makes help links from the kernel match those already populated from the template

IPython/html/static/notebook/js/menubar.js

@@ -394,10 +394,12 define([
                     .attr('target', '_blank')
                     .attr('title', 'Opens in a new window')
                     .attr('href', link.url)
-                    .text(link.text)
                     .append($("<i>")
                         .addClass("fa fa-external-link menu-icon pull-right")
                     )
+                    .append($("<span>")
+                        .text(link.text)
+                    )
                 )
             );
             cursor = cursor.next();