notebook "Last saved:" is misleading on file opening.

[ivanov]

When opening a notebook, our javascript currently informs the user that the file was last saved at the time of opening.

frontend/html/notebook/static/js/savewidget.js:

    SaveWidget.prototype.set_last_saved = function () {
        var d = new Date();
        this.set_save_status('Last saved: '+d.format('mmm dd h:MM TT'));
    };

It be great if this was actually the mtime of the file on the notebook server - that way you could actually keep track of when the file was actually last changed / saved, which is more informative than telling you when you opened the notebook

[minrk]

The information is no longer inaccurate - there is a checkpoint date and bool 'autosaved' state, so no misleading 'last saved' date.