Deprecate deviance and replace with mean_residual_deviance in as input for all functions
The official term that we use for this metric is "mean_residual_deviance". The metrics helper functions use that and that's the name of the column in any regression metrics output data.frame. All the other performance metrics use the same name universally in H2O, so this one is an inconsistency since we use "deviance" whenever its in a list of options in R and Python, but "mean_residual_deviance" everywhere else.
For backwards compatibility, we can map "deviance" -> "mean_residual_deviance" in the client before we check the value, and then throw a deprecation warning as well.