Model prediction / regression selection

[ceholden]

Allow users to specify the regression or prediction model used within the online monitoring approach. We're using LASSO with a fixed lambda because of legacy CCDC reasons, but there's no reason we couldn't move toward more algorithms.

A short list of interesting ones:

• LASSO with fixed lambda
• LASSO with cross-validated lambda
• Ridge regression with and without CV
• Elastic Net
• Theil Sen regression
• RANSAC
• OLS
• WLS