More updates

Supersedes https://github.com/modcloth/docker-builder/pull/56

- [x] more granular pushes (addresses https://github.com/modcloth/docker-builder/issues/31)
- [x] delete temporary uuid tag (addresses https://github.com/modcloth/docker-builder/issues/26)
- [x] implement server functionality and envconfig (addresses https://github.com/modcloth/docker-builder/issues/17 and https://github.com/modcloth/docker-builder/issues/55)