Fix loading subscriptions on the live site.

For some reason on both my and Waseem's local instances the lack of a
trailing slash was not an issue, but this does fix the issue on the
live site.

This could be because we are running Django 1.4.1 and the deployment
server is running 1.4.0.

(imported from commit 613732d75f204fd654247382088d92879780560b)

zephyr/static/js/zephyr.js

@@ -42,7 +42,7 @@ $(function () {
     $('#sidebar a[href="#subscriptions"]').click(function () {
         $.ajax({
             type:     'GET',
-            url:      'json/subscriptions',
+            url:      'json/subscriptions/',
             dataType: 'json',
             timeout:  10*1000,
             success: function (data) {