List all tokens in the store.

    :param opts: Salt master config options
    :returns: List of dicts (token_data)

def list_tokens(opts):
    '''
    List all tokens in the store.

    :param opts: Salt master config options
    :returns: List of dicts (token_data)
    '''
    ret = []
    redis_client = _redis_client(opts)
    if not redis_client:
        return []
    serial = salt.payload.Serial(opts)
    try:
        return [k.decode('utf8') for k in redis_client.keys()]
    except Exception as err:
        log.warning('Failed to list keys: %s', err)
        return []