Compute the log loss for models with binary outcome.

## Details

Logistic regression models predict the probability of an outcome of being a
"success" or "failure" (or 1 and 0 etc.). `performance_logloss()`

evaluates
how good or bad the predicted probabilities are. High values indicate bad
predictions, while low values indicate good predictions. The lower the
log-loss, the better the model predicts the outcome.