Removing unused import
Added name and class_name properties for JobWriter

This is needed for fixing issue #4.
See http://github.com/meisam/YSmart/issues/issue/4
Fixed #4 TPCH q21's output does match the output of C/Java-ish YSmart

Some of the created child jobs were being ignored because they were not
being added to the list of currently created jobs.

See http://github.com/meisam/YSmart/issues/issue/4