Add specs for Commit.winner_count

Also refactor for clarity and brevity
Get better names in mapping using group splatting

Array#[] only is not particularly clear in nested mappings. Use the
splat group to give names to these values within each iteration.
Switch to method class of hash-like key lookups

Since we are using `Struct` for our winner display page, use the method
calls instead of the `Struct#[]` style.