HTTPClient now supports a retries argument. It will reissue requests
for any 5xx or socket (400 with n/a) errors. This retry loop was
"inspired" by swiftclient's loop. It reauths one extra time if
necessary. It uses backoff times of 1, 2, 4... seconds.
The default is 0 retries. It is also exposed to the shell as well with
a --retries arg.
Change-Id: I67bed02d65155f4a4d5d879bb233f56cc78849fa
112bd60d4e