Add options specific to logs subcommand.

def _logs_options(p):
    """ Add options specific to logs subcommand. """
    _default_options(p, blacklist=['cache', 'quiet'])

    # default time range is 0 to "now" (to include all log entries)
    p.add_argument(
        '--start',
        default='the beginning',  # invalid, will result in 0
        help='Start date and/or time',
    )
    p.add_argument(
        '--end',
        default=datetime.now().strftime('%c'),
        help='End date and/or time',
    )