Update Capfile

To deploy to the new server, and to deploy from the temporary migration
branch.
Add Readme

This documents the steps you'll need to complete in order to both get
the backup script running locally, and to get it deployed using Recap.
Update bundled Gems

The box we're moving to is running Ruby 2.1 so we can relax the
restriction on the versions of the gems we're including. I ran `bundle
update` after removing the version restrictions.