Implement AutoUpload option in advanced settings

Template assets (css/js/img/etc) will be automatically uploaded only if
AutoUpload is set.
Manual upload will always override this option.
HTML snippets are always updated through the API, whatever AutoUpload
is set to.
Display current action as the 1st item in the tray menu

On lock(), replace 1st menu item with "updating {file}", display
previous label on unlock()