Updating base image to use a new base and builder image.
Updating base image to use a new base and builder image.

New Images are based on Ruby built from source on top of Minideb  (https://github.com/bitnami/minideb)

Base image repo, for more info:
https://github.com/alphagov/govuk-ruby-images

Further details:
https://trello.com/c/Zy0fd25w/970-use-base-builder-images-in-all-the-app-dockerfiles

alphagov/static,alphagov/static,alphagov/static