rgw: aws4: handle UNSIGNED-PAYLOAD under header auth

[jmunhoz]

Fixes: http://tracker.ceph.com/issues/15499

Signed-off-by: Javier M. Mellid jmunhoz@igalia.com

[jmunhoz]

In the jargon of AWS S3, this patch adds the missing bits to handle the 'Unsigned payload option' in 'Transfer Payload in a Single Chunk' (Authorization Header way)

s3-tests has not coverage for the combo (PUT + UNSIGNED-PAYLOAD + Authorization Header) cause our test cases use boto2 with the 'Signed payload option' mainly. Testing with libcloud requires changing the host/region to speak to RGW and using the verify_hash=False parameter in 'driver.upload_object' method.

One RGW S3 provider in libcloud is almost finished but I am running some testing before asking to go upstream in libcloud for the next days.

[yehudasa]

lgtm