MAPREDUCE-5148. Fix MAPREDUCE-4970 to ensure task-log4j.properties is available for previous installs by putting it in hadoop-core.jar. Contributed by Arun C. Murthy.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-1@1480447 13f79535-47bb-0310-9956-ffa450edef68