Be on the correct Filesystem for output to S3.

#169 change to move rather than copy to output breaks Scoobi on AWS
Elastic MapReduce for a standard usecase where HDFS is the temporary
filesystem and output to S3.

Making the output directories on the right FileSystem in `MapReduceJob`
is a fix. The foreign test in `FileSystems.moveTo` covers matters until
#76 is addressed.