Add required deps for publishing to Artifactory
Optionally publish to Artifactory using the Omnibus publisher

If the release script is called with the `—-publish-to-artifactory`
option each artifact will be published to Artifactory in addition to the
normal Omnitruck publishing tasks.
Merge pull request #226 from opscode/schisamo/publish-to-artifactory

Optionally publish to Artifactory using the Omnibus publisher