Add bootstrapping for confidence intervals

[FabianKruger]

• add possibility to bootstrap data to generate confidence intervals to ROC curve and for AUROC value

[joshuawe]

Very nice idea

Should this be done for all plots???

[joshuawe]

Plots for which it needs to be done:

• [x] ROC Curve
• [x] Calibration Curve
• [ ] Accuracy
• [ ] Classification Matrix
• [ ] Confusion Matrix