Replace the unit page with the container page

STUD-1754
I think you should be able to use xblockInfo.save as in this cde in xblock_editor.js:

````
save: function(options) {
                var xblockInfo = this.model,
                    data,
                    saving;
                data = this.getXModuleData();
                if (data) {
                    saving = new NotificationView.Mini({
                        title: gettext('Saving&hellip;')
                    });
                    saving.show();
                    return xblockInfo.save(data).done(function() {
                        var success = options.success;
                        saving.hide();
                        if (success) {
                            success();
                        }
                    });
                }
            },
````