Leaderboard not sorted by metric value

[SuryaThiru]

The leaderboard tables in the output leaderboard.csv and the README.md are not sorted by the metric value. It will be convenient to compare and review our models if they are sorted.

Is there a way to identify if the metric is greater_is_better from this method?

[pplonski]

Right now, the models appear on the leaderboard in the order in which they were trained.

We can add sorting in get_leaderboard() but please add a method in the Metric class that will return the direction of sorting.

@SuryaThiru would you like to PR on this issue?

[SuryaThiru]

Is a Metric class object accessible from get_leaderboard() ? I only noticed the metric names being used.