AWS Toolkit for Eclipse

With better Amazon S3 integration, in the Bundle AMI Dialog, we could:
- display a user's existing buckets in a drop down instead of requiring
the user to type them out
- perform error checking for existing/valid bucket names when a user
enters a new bucket name

This involves:
- Getting access to an Amazon S3 client library
- Querying for a user's existing buckets and displaying them in a new drop
down list
- If the user chooses to create a new bucket, we need to validate that the
bucket name isn't already in use and can be created