roc.plot: Create ROC Curves
In Ehsan-F/R-Mixtape: Mixtape: Enhancing the model making process

Create ROC curves for train and test datasets.

1	roc.plot(prob = 'p_', y = "t_Paid", df_train = ds1, df_test = ds2, model = NULL, model_var = 'X1')

`prob`	The prediction made by the model; should be between 0, 1.
`y`	The observed data; should be binary.
`df_train`	Train data.
`df_test`	Test data.
`model`	The name of the model in focus. If not NULL, then predictions are made directly through this function and the prob argument only acts as the name for the predicted variable.
`model_var`	If model prediction is of type "prob", then the name of the required predicted variable. By default this is "X1" which indicates the probability of the event.