Rename predict and evaluation functions

See how evaluate and predict functions are used. It seems that

• predict is an evaluation function (and should be renamed evaluate)
• evaluate is used to run validation (and should be renamed validate)

changed milestone to %DAN-P5: Improve training

added P2 Quick Win labels

assigned to @mblanco

mentioned in merge request !253 (merged)

closed with merge request !253 (merged)