Create official 'movableink/doorman' Docker image on Docker Hub

[pataquets]

Create an 'official', based on your repo, automated build at Docker Hub for the image: https://docs.docker.com/docker-hub/builds/ . Just requires a free Docker Hub account and a following a quick 'Create automated build' process where you link your Github repo to the Docker Hub.

An Automated Build provides a trustable, verifiable from source, public image on Docker Hub which can be used right away by just docker runing the image (movableink/doorman). It will add another packaging/distribution/installation method, which will be triggered automatically on each commit.

Ping me if I can be of any help.

[pataquets]

Bump.
Having an official image would also enable adding usage docs referencing the image built from this very same code.

[pataquets]

See also #35

[pataquets]

@mnutt is this user/image owned by you? https://hub.docker.com/r/movableink/doorman/
To be it as trustworthy as possible, it should be an Automated Build, ideally. Thus, it would be auditable.