An initial stab at an RDD for Variant Store.

This `foreach` here is an RDD action, so the `println` will occur on whichever worker happens to process this slice of data on the cluster. 

Use `collect` after `filter` to bring the results to the driver, then  `foreach` on the local Seq. This will cause the results to be printed locally. (See https://github.com/elmer-garduno/spark-examples/blob/docs_run_on_gcloud/src/main/scala/com/google/cloud/genomics/spark/examples/SearchReadsExample.scala#L102)