HADOOP-9361 change how the s3n error handler recurses down: the original exception is passed down and thrown up at the end; IOExceptions aren't wrapped
HADOOP-9361 complete all docs that it's resources/contract-test-options.xml
HADOOP-9361 fix deprecation warning of makeQualified by inline expanding it
HADOOP-9361 fix findbug warning of unused private method in FTPFileSystem