Remove metadata from leadrboard.RDS

[tmastny]

Seed meta-data in particular inflates the size of the leadrboard.RDS and the loading speed. The idea was to provide a function (which hasn't been implemented #5) that could recreate or redocument the exact model.

However, I haven't actually needed to do this in any of my work. The most useful feature has just been the leader board. I should consider removing this meta-data, or putting it in another file.

[tmastny]

For example, in my second contest, my leadrboard.RDS file was 60 mb with only ~60 models.

[tmastny]

I think I should implement and resolve #21 before I worry about this. Avoid premature optimization.