FLIP-111: Docker image unification

Flink Docker Integration Improvements Flink community encourages users to use or extend the official Docker Hub image for Flink [1] in the deployments. You can now also run the Flink image in the Job Cluster mode. The user documentation for Flink Docker integration has been reworked, please check the updated documentation [2]. It now includes examples for Session and Job cluster deployments with: - docker run [3] - docker compose [4] - docker swarm [5] - standalone Kubernetes [6] See also how to customize the Flink image [7]: configuration options, logging, plugins, adding more dependencies and installing software. The corresponding example scripts in the Flink Github repository [8] have been removed and will no longer be supported, including the examples of integration with Bluemix. Therefore, the following modules have been deleted in Flink Github repository: - flink-contrib/docker-flink - flink-container/docker - flink-container/kubernetes [1] https://hub.docker.com/_/flink [2] https://ci.apache.org/projects/flink/flink-docs-master/ops/deployment/docker.html [3] https://ci.apache.org/projects/flink/flink-docs-master/ops/deployment/docker.html#how-to-run-flink-image [4] https://ci.apache.org/projects/flink/flink-docs-master/ops/deployment/docker.html#flink-with-docker-compose [5] https://ci.apache.org/projects/flink/flink-docs-master/ops/deployment/docker.html#flink-with-docker-swarm [6] https://ci.apache.org/projects/flink/flink-docs-master/ops/deployment/kubernetes.html [7] https://ci.apache.org/projects/flink/flink-docs-master/ops/deployment/docker.html#customize-flink-image [8] https://github.com/apache/flink