HDFS-5365. Merging change r1533575 from branch-2 to branch-2.2

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2.2@1533577 13f79535-47bb-0310-9956-ffa450edef68
MAPREDUCE-5457. Add a KeyOnlyTextOutputReader to enable streaming to write out text files without separators (Sandy Ryza)

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/branches/branch-2.2@1533625 13f79535-47bb-0310-9956-ffa450edef68