[scripts,engine] Implement fixes on evaluation (closes #20), and prepare for...

[scripts,engine] Implement fixes on evaluation (closes #20), and prepare for MLflow integration (issue #60)

* Use average-precision instead of AUC for precision-recall figures
* Report average precision on tables
* Include dependence on credible (prepare to handle issue #43)
* Also saves result table in JSON format (prepare to handle issue #60)