Implement fixes on evaluation (closes #20), and prepare for handling issue #60

Implement fixes on evaluation (closes #20 (closed)), and prepare for MLflow integration (issue #60 (closed))

• 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 (closed))
• Consolidate train/prediction functions to output run/parameter metadata in JSON format