HDFS-5338. Add a conf to disable hostname check in datanode registration.


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1532468 13f79535-47bb-0310-9956-ffa450edef68
HADOOP-100046. Print a log message when SSL is enabled (David S. Wang via wang)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1532477 13f79535-47bb-0310-9956-ffa450edef68
Merge remote branch 'origin/trunk' into trunk-gd
Merge remote branch 'origin/trunk-gd' into fb-HADOOP-9291-trunk-gd