set default autosave interval to two minutes

IPython/frontend/html/notebook/static/js/notebook.js

@@ -43,7 +43,8 b' var IPython = (function (IPython) {'
         this.last_checkpoint = null;
         this.autosave_interval = 0;
         this.autosave_timer = null;
-        this.minimum_autosave_interval = 30000;
+        // autosave *at most* every two minutes
+        this.minimum_autosave_interval = 120000;
         // single worksheet for now
         this.worksheet_metadata = {};
         this.control_key_active = false;

IPython/frontend/html/notebook/static/js/notebookmain.js

@@ -87,7 +87,7 b' $(document).ready(function () {'
             document.location.hash = '';
             document.location.hash = hash;
         }
-        IPython.notebook.autosave_notebook(30000);
+        IPython.notebook.autosave_notebook(IPython.notebook.minimum_autosave_interval);
         // only do this once
         $([IPython.events]).off('notebook_loaded.Notebook', first_load);
     };