Automatically normalize covariate values

[schuemie]

Large covariate values ( > 1 ) can lead to numeric overflow errors. We currently solve this by dividing the covariate value by the max value for that covariate before loading into Cyclops. It would be nice if Cyclops did this automatically, and rescales the beta coefficients so the normalization is invisible to the user.

For consistency we should also automatically scale the prior for each covariate.

In addition, we could add the option to automatically scale the prior by the standard deviation of the covariate (instead of the max).