Currently, using `-libjars` requires something like this:
--bootstrap-file myjar.jar --bootstrap-cmd 'cp myjar.jar /home/hadoop/myjar.jar' --hadoop-arg -libjars --hadoop-arg /home/hadoop/myjar.jar
It would be nice if we could do this instead:
--libjars myjar.jar
mrjob would:
* Upload the file like the other bootstrap files
* Copy it to a unique location like /tmp/myjar-235324.jar
* Add the appropriate `-libjars` arguments to `StreamingStep.step_args`