Fix PUDBEV-2372: resolve slight difference in Gains/Lift computation. Wasn't counting the number of observations in each group, but just using N/groups, which wasn't exactly right.
Fix PUDBEV-2372: resolve slight difference in Gains/Lift computation. Wasn't counting the number of observations in each group, but just using N/groups, which wasn't exactly right.

h2oai/h2o-dev,h2oai/h2o-3,michalkurka/h2o-3,YzPaul3/h2o-3,mathemage/h2o-3,spennihana/h2o-3,h2oai/h2o-3,h2oai/h2o-3,h2oai/h2o-dev,h2oai/h2o-dev,jangorecki/h2o-3,h2oai/h2o-3,h2oai/h2o-dev,mathemage/h2o-3,h2oai/h2o-dev,h2oai/h2o-3,jangorecki/h2o-3,jangorecki/h2o-3,h2oai/h2o-3,mathemage/h2o-3,h2oai/h2o-3,YzPaul3/h2o-3,mathemage/h2o-3,YzPaul3/h2o-3,spennihana/h2o-3,michalkurka/h2o-3,jangorecki/h2o-3,mathemage/h2o-3,jangorecki/h2o-3,spennihana/h2o-3,YzPaul3/h2o-3,michalkurka/h2o-3,spennihana/h2o-3,h2oai/h2o-dev,michalkurka/h2o-3,YzPaul3/h2o-3,michalkurka/h2o-3,YzPaul3/h2o-3,mathemage/h2o-3,jangorecki/h2o-3,michalkurka/h2o-3,spennihana/h2o-3,michalkurka/h2o-3,h2oai/h2o-3,jangorecki/h2o-3,YzPaul3/h2o-3,h2oai/h2o-dev,mathemage/h2o-3,spennihana/h2o-3,spennihana/h2o-3