dockerhub automated builds suck

[buhman]

current problems:

• can't customize readme on automated builds
• can't do automated builds for non-x86_64 architectures

Could probably solve both by:

• switching to manual builds, and doing dockhub pushes via circleci
• some people use qemu hackery on circleci as well; not a horrible idea, and probably not that hard

[buhman]

Related, should probably environment-variable-ifiy more of the configuration, and document it. I did do this at some point, but it got eaten by dockerhub.