Publish Docker images during the pipeline
In an effort to speed up the docker job, this will publish an image of
master under Docker's ci tag. This image will hopefully save us time
in future builds, especially ones that don't introduce new requirements.
Both this new job and the existing docker job are being placed in a
new stage of the pipeline that will only run if the other jobs pass.
Closes #51 (closed)
Edited by Andy Dirnberger