Anomaly changes

Follow up to #956 by @breznak 

CC @subutai @oxtopus @rhyolight 

- [X] - The anomaly class supports taking either current predicted columns or previously predicted columns. I don't see any reason to have the class support both. Rather than duplicating the previously predicted state I think the new class should take the previously predicted only. (d9ecf61)
- [X] - I don't think we use the KNNAnomalyClassifierRegion but the change there added state to the class with no benefit. It should just use computeRawAnomalyScore. (d5f383b)

Other changes:

- Clean ups (1ad37c0, c8f2af3)