no automatic rebuild of container images on docker hub

[L4R5]

The current container image on docker hub is already 3 months old. The latest commit fixed a problem I have with the current image.
Please enable automatic container image build after git push.

[jhunt]

My main concern with this is the open-ness of this org - there are over 250 people in this org, and they aren't all necessarily on the same page re: security conscience. Will have to investigate the impacts of wiring up Docker Hub to Git Hub when the GH org is so wide and diverse.

[jhunt]

(but I 💯 agree that auto-builds would make everyone's lives easier)