2.2.0-k8s-0.3.0

Merge pull request apache-spark-on-k8s#422 from liyinan926/branch-2.1…

…-kubernetes

Update pom to v0.3.1 for the new 2.1 release

Update pom to v0.3.0 of spark-kubernetes (apache-spark-on-k8s#385)

Preparing Spark release v2.2.0-rc6

POM update 0.2.0 (apache-spark-on-k8s#329)

Preparing Spark release v2.1.1-rc4

Updating images in doc (apache-spark-on-k8s#218)

Preparing Spark release v2.1.1-rc2

Preparing Spark release v2.1.1-rc1

Update tags on docker images. (apache-spark-on-k8s#194)