MAPREDUCE-5837. MRAppMaster fails when checking on uber mode. Contributed by Haohui Mai.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1589903 13f79535-47bb-0310-9956-ffa450edef68
HADOOP-10535. Make the retry numbers in ActiveStandbyElector configurable. Contributed by Jing Zhao.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1589905 13f79535-47bb-0310-9956-ffa450edef68