Add Amazon Web Services SDK to 3rdparty for Amazon S3 external storage

3rdparty/aws-sdk/README.md

3rdparty/aws-sdk/_compatibility_test/README.md

...rty/aws-sdk/_compatibility_test/sdk_compatibility.inc.php

...ty/aws-sdk/_compatibility_test/sdk_compatibility_test.php

...ws-sdk/_compatibility_test/sdk_compatibility_test_cli.php

3rdparty/aws-sdk/_docs/CHANGELOG.md

3rdparty/aws-sdk/_docs/CONTRIBUTORS.md

3rdparty/aws-sdk/_docs/DYNAMODBSESSIONHANDLER.html

3rdparty/aws-sdk/_docs/KNOWNISSUES.md

3rdparty/aws-sdk/_docs/LICENSE.md

3rdparty/aws-sdk/_docs/NOTICE.md

3rdparty/aws-sdk/_docs/STREAMWRAPPER_README.html

3rdparty/aws-sdk/_docs/WHERE_IS_THE_API_REFERENCE.md

3rdparty/aws-sdk/authentication/signable.interface.php

3rdparty/aws-sdk/authentication/signature_v2query.class.php

3rdparty/aws-sdk/authentication/signature_v3json.class.php

3rdparty/aws-sdk/authentication/signature_v3query.class.php

3rdparty/aws-sdk/authentication/signature_v4json.class.php

3rdparty/aws-sdk/authentication/signature_v4query.class.php

3rdparty/aws-sdk/authentication/signer.abstract.php