upgrade to aws-java-sdk-1.9.3

As of 1.9.0, the aws-java-sdk has been
broken up into multiple projects. This
change also changes the dependency to
just the cloudwatch and autoscaling
libraries that we use.
Merge pull request #286 from brharrington/aws-java-sdk-1.9.3

upgrade to aws-java-sdk-1.9.3