GET requests and the payload parameter

[asgeirb]

In GET requests one must provide :payload "" in order to generate valid signatures. This is confusing and unnecessary.

This creates an invalid signature:
(aws-sign4:aws-sign4 :region :us-east-1
:service "route53"
:method :get
:host "route53.amazonaws.com"
:path "/2013-04-01/hostedzone")

This generates a valid signature:
(aws-sign4:aws-sign4 :region :us-east-1
:service "route53"
:method :get
:payload ""
:host "route53.amazonaws.com"
:path "/2013-04-01/hostedzone")

[asgeirb]

Looking at the code I see payload=nil creates a UNSIGNED-PAYLOAD request (used in s3), but maybe there should be a special case for GET requests (as unsigned-payload is not relevant)