public void selectFolder(@Nullable final Uri startUri) {
        selectFolderInternal(SelectAction.SELECT_FOLDER, null, startUri, null);
    }
Asks user to select a folder for single-time-usage (location and permission is not persisted)
if a callback for action {@link SelectAction#SELECT_FOLDER} is registered, it will be called after selection has finished
main/src/main/java/cgeo/geocaching/storage/ContentStorageActivityHelper.java