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.
There was a followup comment on the usage of prepareResponse to use a POJO for the result. Are we not planning on doing that? If so, would be good to know why.