run export across accounts and log groups specified in config.

def run(config, start, end, accounts, region, debug):
    """run export across accounts and log groups specified in config."""
    config = validate.callback(config)
    destination = config.get('destination')
    start = start and parse(start) or start
    end = end and parse(end) or datetime.now()
    executor = debug and MainThreadExecutor or ThreadPoolExecutor
    with executor(max_workers=32) as w:
        futures = {}
        for account in config.get('accounts', ()):
            if accounts and account['name'] not in accounts:
                continue
            futures[
                w.submit(process_account, account, start,
                         end, destination, region)] = account
        for f in as_completed(futures):
            account = futures[f]
            if f.exception():
                log.error("Error on account %s err: %s",
                          account['name'], f.exception())
            log.info("Completed %s", account['name'])