Enable Docker hub automatic build

[ChihChengLiang]

What is wrong?

Since we are beginning to work on better versioning management in the codebase, it would make sense to automatic build images in Docker hub whenever a new version is released.

That said, we are just one step closer to have the automatic build. There is a bug that the build process would fail in Docker hub in the COPY step.

How can it be fixed?

• A workaround for https://github.com/docker/hub-feedback/issues/811 is to make sure the destination of COPY must be an explicitly named directory. For example,
  • COPY . ./ bad
  • COPY . ./bin good