CDAP-713: Updated SparkPageRank archetype according to migration to services.

@rohitsinha54 @sreevatsanraman The archetypes of SparkPageRank app have been updated regarding to migration from procedures to services. Scripts also have been updated (same as in #704). Please take a look.
Should this not be "Spark program"? I understand from Rohit that is the preferred expression, as Spark programs can contain multiple jobs...