CANN API Client for Go - retry on failed attempts

Retries on failed attempts.

Download will retry, in the same session, if not successful; up to 3 times per session.

If connection is reset (by the source), download will be postponed until the next session (i.e. 48 hours).

Please, see README.md

ICANN API Client for Go - enhanced authentication

Access Token is now kept on disk.

Authentication re-tries in 2 minutes, if status code is 0.

Please, see README.md