HDFS-4982. JournalNode should relogin from keytab before fetching logs from other JNs. Contributed by Todd Lipcon.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1502683 13f79535-47bb-0310-9956-ffa450edef68
HADOOP-9703.  org.apache.hadoop.ipc.Client leaks threads on stop (Tsuyoshi OZAWA via Colin Patrick McCabe)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1502704 13f79535-47bb-0310-9956-ffa450edef68
Merge remote branch 'origin/branch-2' into branch-2-gd
Merge remote branch 'origin/branch-2-gd' into fb-YARN-474-branch-2-gd