Upload Docker image to Docker Hub

[nvllsvm]

In addition to using it as a base image, it allows one to copy the env-aws-params binary to their image using a multi-stage build. Unlike a URL to the binary, I can actually remember the name of a Docker image. :)

For example.

FROM python:alpine
COPY --from=gmr/env-aws-params:alpine /usr/bin/env-aws-params /usr/bin/
...
ENTRYPOINT ["/usr/bin/env-aws-params"]
CMD python-app