Show elapsed time support for Ambrose-Hive

The elapsed time feature didn't work for Hive runtime. AmbroseHiveStatPublisher now
instantiates MapReduceJobState with args where the elapsed time is initialized/maintained.
Further fixes/improvements:

- counterGroupMap was missing from event file
- new demo example (has more pretty DAG)
- resolve internal join alias name
- HiveJobTest: add testing metrics in event json
- minor indentation issues