recording metrics through FG

[raynardj]

recording the return metrics in to database

The function in the class forgedb will include

• registering new metric
• keep a record in the log
• check if this is the best performance

The function in the ftorch

• collect Trainer result(a dictionary) automatically

[raynardj]

if Trainer(..... callbacks = [fg.metrics()]) was set, the metrics will be saved automatically