WIP. Adding A/B/C Testing

`next if`/`next unless` is a ruby idiom that sometimes makes loops like this clearer (if you subscribe to the "thing you want to do in the normal case should not be inside multiple nested loops" philosophy), eg:
````
    Activity.connection.execute(query).each do |level_source_id, level_id, count|
      next unless level_source_id && level_id
      level_source = LevelSource.find(level_source_id)
      next unless level_source.is_standardized?
````