Update Turbolinks, load additional assets only on request, fix JS

Signed-off-by: Sebastian Serth <Sebastian.Serth@student.hpi.de>

app/assets/javascripts/editor/ajax.js

@@ -0,0 +1,16 @@
+CodeOceanEditorAJAX = {
+  ajax: function(options) {
+    return $.ajax(_.extend({
+      dataType: 'json',
+      method: 'POST',
+    }, options));
+  },
+
+  ajaxError: function(response) {
+    var message = ((response || {}).responseJSON || {}).message || '';
+
+    $.flash.danger({
+      text: message.length > 0 ? message : $('#flash').data('message-failure')
+    });
+  }
+};