Upgrade aws sdk v2

[zacwolfe]

This code upgrades the project to AWS SDK v2. The unit test and sample code has been updated to use the new async APIs. It should be noted that the intention of this work was merely to get things working with the v2 SDK while employing minimal effort. By no means should the updated code in the sample or unit tests be considered exemplary models of how these APIs should be employed in production environments.

[sivaprasadreddy]

@zacwolfe Hey, this is excellent. I will take a deep look at the PR soon and let you know.