Build docker image in circleci

[briggySmalls]

Currently the docker image is built on dockerhub.

However the documentation, which is built in circle CI, depends on this docker image.

Changes to the documentation and archie may well occur simultaneously (it is documentation after all!) which might mean that we get stuck in a dependency cycle: docs require latest archie, but latest archie can't be built until committed to master.

Building the docker container in circleci should make it available immediately