SignatureV4: don't depend on Method type form Aws.Core
General: JSON instances for Arn
SQS: change SQS API version to "2012-11-05"  (enables support of WaitTimeSeconds)
SQS.Message: add parameter rmWaitTimeSeconds for optional long polling
Sns.Publish: fix query parameter name of Publish command
Sns.Publish: add data type for SQS notification message
tests/Sns/Main.hs: add test for integration of SNS and SQS