ST-2029: Initial commit of schema registry docker image

[elismaga]

I have extracted the docker file and dependent scripts from cp-docker-images for schema registry into this new repo.

• This build will use maven and the docker plugin to build the image.
• This image will be built from the new cp base image.
• This script will also install schema registry using a pre-built package.
• This job will be executed downstream of the packaging build and the confluent version and packaging build number will be passed in as parameters.

This is an initial version of these scripts and will not be enabled right away. I would like to get this pushed to the master branch so that I can begin testing this out by running it after the packaging build, but this will not replace our current / official images until the actual roll out.

[elismaga]

minor questions, but generally looks good. nodeLabel and TODO stuff also same as other PRs.

I'm assuming large chunks of this are basically unchanged (e.g. the dockerfile itself, support cub/dub stuff, etc), so not looking as closely at those. let me know if they have changed in any significant way.

The only significant change to the docker file is that i add our packaging repo to apt-get so that we can install the packages from that repo.