Changes for HDFS-3042 branch. This change list will be merged into the trunk CHANGES.txt when the HDFS-3-42 branch is merged. ------------------------------ HADOOP-8220. ZKFailoverController doesn't handle failure to become active correctly (todd) HADOOP-8228. Auto HA: Refactor tests and add stress tests. (todd) HADOOP-8215. Security support for ZK Failover controller (todd) HADOOP-8245. Fix flakiness in TestZKFailoverController (todd)