This update migrates the HDS system source and build from Java 8 to Java 11.
I had to get Java 11 runtime into the Docker build. To achieve this, it was
easiest to migrate the image base image from Ubuntu 16.04 LTS to 18.04 LTS and
this, in turn, required that a newer build of the hvif2png tool had to be setup.
It all seems to be working well locally.
I would like to get this deployed independently of any other changes and let it
settle because otherwise it may be difficult to attribute problems to this
upgrade. Alex; can you please try to deploy this when you get a spare moment.