add an example that runs wordcount over file datasets
renamed app to FileSetExample; addressed John's comments
addressing more of JJ's comments
Merge branch 'feature/file-example' into develop
Spark Integration: fix failing spark unit test
Merge pull request #681 from caskdata/feature/fix-spark-unit

Spark Integration: fix failing spark unit test
Merge branch 'develop' of github.com:caskdata/cdap into feature/CDAP-512-DefaultServiceMetrics
Addressing comments