Add support for S3 Buckets

Hi guys,
Sorry it took so long to get this out, life n that got in the way.

This PR adds module and state support for S3 buckets (`aws_bucket`). It's pretty straightforward right now - you can only create/destroy buckets.

I've added an `aws_file` module that moves files to and from S3. In the long run, this is intended to replace the `s3` module. The setup is the same as work `aws_sqs`.

I'll get the test stuff up and running shortly.