Hadoop java shim: implement Qfs file system object as subclass derived from org.apache.hadoop.fs.AbstractFileSystem in order to make QFS work with Yarn. Make QuantcastFileSystem setWorkingDirectory() with initialize method by maintaining working directory fully qualified. Fix QFSEmulationImpl fullStat method by returning only "path" of the uri instead of fully qualified uri, exactly as QFSImpl does, in order to make "emulation" which uses local file system work with fully qualified path. Add overloaded create version with "append" flag to IFS interface, QFSImpl, and  QFSEmulationImpl. Update Hadoop shim build versions to use the more recent stable versions for each Hadoop version line.