Cutting a new Spark 2.1 release

[foxish]

This is a prerequisite to announcing upstream.

Steps:

1. Build a distribution with and without hadoop
2. Tag the commit, draft a github release, and upload the tar.gz files in (1)
3. Build and upload the images (appropriately tagged) to the kubespark repo
4. Fill in the release description on GitHub

@apache-spark-on-k8s/contributors

"blocking" PRs:

1. Update pom to v0.3.1 for the new 2.1 release #422
2. Cherrypick fix other py files to 2.1 #415
3. Flag-guard expensive DNS lookup of cluster node full names, part of HDFS locality support #412

[kimoonkim]

Maybe we also want the bug fix #412, which seems almost ready to merge? The bug may impact many large jobs even when they don't use HDFS.

[foxish]

You mean #412? Yeah, I think that's a good one to include as well!

[kimoonkim]

Correct. #412.

[foxish]

PSA: Need an owner from the community for cutting this release. @erikerlandson is doing the 2.2 one, any volunteers for this? @apache-spark-on-k8s/contributors

[liyinan926]

@foxish I can help on cutting a new 2.1 release.

[liyinan926]

@foxish I don't seem to have permission to create a release.

[liyinan926]

Still need to build and upload the new images.

[liyinan926]

Published all images tagged with v2.1.0-kubernetes-0.3.1.