public void selectFile(@Nullable final String type, @Nullable final Uri startUri) {
        selectFilesInternal(type, startUri, SelectAction.SELECT_FILE, null);
    }
Asks user to select a file for single usage (e.g. to import something into c:geo
if a callback for action {@link SelectAction#SELECT_FILE} is registered, it will be called after selection has finished

@param type     mime type, used for intent search
@param startUri hint for intent where to start search
main/src/main/java/cgeo/geocaching/storage/ContentStorageActivityHelper.java