building for scala 2.11, update to latest aws-sdk

Hi,
would be nice to upgrade Scalazon for Scala 2.11.
To get everything to compile i had to remove the sbt-dependency-graph plugin as there is no
binary for 2.11 yet. I also upgraded the aws-java-sdk to the latest version.
The unit test passes. You like to merge back my changes? If latest=greatest is not an option, an alternative would be to setup sbt for cross-building.

Best regards,
Jan