HADOOP-9361 "extending" the spec document, update fsdatainputstream spec
HADOOP-9361 ftp test to recognise and swallow tests where the FS tries to rename into a different directory
HADOOP-9361  tuning core contract base test classes: assertFileExists to throw FileNotFound; add a default timeout of 180s for each test (subclasses may override)
HADOOP-9361  TestHDFSAppendContract to downgrade failure of rename during append -known feature
HADOOP-9361  AbstractRenameContractTest switches to lower case names and changes the ordering of the test assertions
HADOOP-9361  AbstractOpenContractTest adds test to verify that a sequence of reads always returns the expected values to the end of the file
HADOOP-10589 HADOOP-9361 : seek(0) is downgraded to a no-op so doesn't trigger any failures; preconditions added for assignments, and the existing instream isn't overwritten until the new one succeeds (i.e. is never set to null until closed)
HADOOP-9361  swift FS t brought closer into line with HDFS (EOFException, ParentNotDirectoryException), tests updated to match.The SwiftNotDirectoryException is obsolete and removed