HADOOP-10610. Upgrade S3n s3.fs.buffer.dir to support multi directories. Contributed by Ted Malaska.

git-svn-id: https://svn.apache.org/repos/asf/hadoop/common/trunk@1611489 13f79535-47bb-0310-9956-ffa450edef68

Conflicts:
	hadoop-common-project/hadoop-common/CHANGES.txt