remove unused roles, and add packer to the repo

[scollazo]

We have a working packer configuration to build atom boxes, we should move it here and build also archivematica vagrant boxes.

On the other side, the elasticsearch replication role available here, doesn't seem to fit with the repo, we should create a new git repo for it.

[sevein]

You have identified some problems and I think they should be addressed separately:

• Packer template for AM Vagrant box: Add packer configuration files artefactual-labs/am-packbuild#40
• Packer template for AtoM: needs a new home and become open source
• This repo contains unused roles, e.g. nfs, ...?
• This repo contains useful roles like ES replication stuff that should be on its own repo