Upgrade to aws-java-sdk 1.9.3 and more logging.

Here's a summary of the patches:
1. Updated to aws-java-sdk 1.9.3
2. Exclude "s3-us-gov-west-1" and "cn-north-1" regions when creating buckets and when testing
3. Use setRegion to enable S3 V4 protocol to make  "eu-central-1" work
4. Catch null pointer for default region
5. Catch S3 Exceptions and log them