Factor out bootstrap step.
Use DEBIAN_FRONTEND=noninteractive.
Expand the docs.
Grab hostname to use from config file (DRY).

Use `execute` to pick up on new hostname to use.
Use default registry, and allow specifying tags.
Add some comments about using the docker registry.
Update docs from private repo.
Add a note about the time it takes to build a new docker image.
Explain better how the image is updated.
Add a note about how HybridDeployment isn't a public repo (and give the proper URL).
Merge pull request #16 from ClusterHQ/refactor-fabfile

Refactor fabfile and use docker registry.