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.
It would be better if we create a POJO to represent the return value. and then we can use the following function. 
-   void sendJson(ProcedureResponse response, Object object) throws IOException;

Advantage of that would be that the contract of the response would be much clear.