Provide the source code for bluedata/cassandra311 (and appconfig)

[snowch]

I am creating some example images for enablement of customers on KD: https://github.com/hpe-container-platform-community/kubedirector-examples

The Cassandra reference app would be an excellent example for training users on KubeDirector app image development but it's very difficult because the Dockerfile and appconfig are not publicly available.