Script MRStat for Hadoop statistics added

Collects job information provided by the history server and provides it as CSV.
Change default number of Reducers

Configured to launch as many reducers as available in the cluster according to the memory-mb setting of reducer task.
ConfigurationTest adjusted accordingly.
Use Snappy as compression codec again

Encountered irregular "Too many fetch failures" errors while running jobs with map output compression set to DefaultCodec.
However tests may now fail locally when no native snappy library is present.
Added some more variations to ConfigurationTest
No return in catch clause.