CDAP-540: Ported RecommendMovieProcedure to MovieRecommendService.

Implemented the MovieRecommendService in according to the RecommendMovieProcedure.
Old implementation is still available to compatibility with current user guides.
@rohitsinha54 Sree is referring to this comment: https://github.com/caskdata/cdap-apps/pull/30#discussion_r20097844

Sree's suggestion is that this method should return a POJO, and then we can use an appropriate send response method to convert to JSON.