Separating out fetching versions and fetching version labels.  Scoping version labels by app name.
Ability to remove a specified set of versions
Updating stub to more closely reflect what the AWS API returns.  Adding stubs for deleting.
Allowing old versions to be cleaned up after deploy.
Updating documentation to include reference to :keep_latest
Allowing for giving versions prefixes to separate environments on a shared stack
Minor clean up
Very general error handling trying to catch an exception when deleting a version that has no source in S3 for some reason.
Extra logging
Catching explicit delete source failure exception.  Adhereing to logging standards elsewhere in app.
Merge pull request #9 from jwickstra/keep_latest_versions

Keep latest versions