Addapted FOS-R to the changes on FOS API and added support for exporting trained models as PMML.

Summary: Currently only the exporting to PMML is supported as R's pmml package doesn't support importing of PMML.

Test Plan: Ran existing; Added test to validate that the saved PMML model can be parsed.

Reviewers: deag, diogo.ferreira, antonio.alegria, miguel.duarte

Reviewed By: diogo.ferreira