svn merge -c 1592703 from trunk for MAPREDUCE-5402. In DynamicInputFormat, change MAX_CHUNKS_TOLERABLE, MAX_CHUNKS_IDEAL, MIN_RECORDS_PER_CHUNK and SPLIT_RATIO to be configurable.


git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2@1592704 13f79535-47bb-0310-9956-ffa450edef68