Implemented AwsSignatureV3.
A small test code re-use, which also increases test coverage :)
Enabled AwsSignatureV3 test coverage reporting.
Enabled the AWS3-HTTPS nonce.
Added nonc testing to the TestAwsSignatureV3::canonicalRequest test.
Added nonce checking to the TestAwsSignatureV3::sign function; this brings the AwsSignatureV3 class to 100% line test coverage.
Enabled the AwsSignatureV3 class documentation in the public API doxygen output.