Fix country ranking bugs

[hburn7]

Fixes a bug with the country ranking algorithm. The ratings collection was not sorted by country, causing this code to basically fail immediately as it is looking for the next item in the list that does not match the current country:

let country_end = country_slice_begin
            .iter()
            .position(|x| x.country != country)
            .unwrap_or(country_slice_begin.len());

Fix was to apply the following before iterating through each country:

ruleset_slice.sort_by(|x, y| x.country.partial_cmp(&y.country).unwrap());

Closes #53