def form_body
      if body.is_a?(Hash)
        body.map do |k,v|
          [AwsRequest.aws_encode(k), AwsRequest.aws_encode(v)].join("=")
        end.join("&")
      else
        body
      end
    end
def form_body
      if body.is_a?(Hash)
        body.map do |k,v|
          [AwsRequest.aws_encode(k), AwsRequest.aws_encode(v)].join("=")
        end.join("&")
      else
        body
      end
    end
Encode the form params if the body is given as a Hash.