Revert "Change the data type from RDD[DB[Double]] to RDD[Vector]"

This reverts commit 4673fd5999bf0c9aeea49ec063a09976c1af3889.
Revert "Revert "Change the data type from RDD[DB[Double]] to RDD[Vector]""

This reverts commit 0dc92208507483286d375b2a0d0fad968e004008.
Add AccuracyTestApp