[EDP] Add a Spark job type (instead of overloading Java)

Spark EDP has been implemented initially using the Java job type. However,
the spark semantics are slightly different and Spark jobs will probably
continue to diverge from Java jobs during future development.  Additionally,
a specific job type will help users distinguish between Spark apps and Java
mapreduce jobs in the Sahara database.

blueprint edp-spark-job-type

Change-Id: I0476d30214b33c08629a02bbdd784d36a4799cf9
Merge "[EDP] Add a Spark job type (instead of overloading Java)"