Java upgrade

[xrl]

The NetflixOSS image is at least a year old

I've borrowed bits from https://github.com/dockerfile/java/tree/master/oracle-java8 and we're doing the java8 install ourselves. We could just ineherit from them but I don't think they publish to the docker registry.

[ches]

Hi @xrl, thanks for working on this, and my apologies for being unresponsive for a long while. Among other things I've been drinking from the firehose at a new $DAYJOB. On the plus side I'm starting to use this container in a work capacity, so hopefully I'll be more attentive to it.

I'm going to merge Kafka version updates and tag image builds for the stable release versions. About the base image change, I'm thinking of switching to an Alpine-based Java image to reduce the image size, so I'll explore this before making the change you've proposed here. Thoughts?

[xrl]

Any change off of the 1+ year old JVM image would be a win. Keep in mind that the repo I use in mine is actively maintained and it drags in the Oracle JVM which is has a reputation for being better optimized than the OpenJDK alternative. But I do like a nice alpine container. In any case, sounds good!