Merge pull request #8 from pmcfadden/master

PatrickMcFadden Using double quotes for string interpolation and fixing ...
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
use minitest embeded by ruby 1.9
make logging patten more consistent
update default config template to include new options :keep_last and :version_prefix
release 0.3.0
should not care about package option if the action is not deploy
Added support for specifying a yaml specification for a package uploaded to s3 in the -p option
bump up version
[issue #10] Fail the deploy when instance provision failed. Idealy ElasticBeanstalk should handle this case correctly