The App calculates Elo

* When a match winner is submitted, the player's elo is upated
* Create CalculateElo class
* Create EloUpdater class
```ruby
def calculate_new_elo(elo, score, expected_score)
  elo + (K_FACTOR * (score + expected_score))
end

def calculate
  get_data
  elos.map.with_index do |elo, index|
    calculate_new_elo(elo, scores[index], expected_scores[index])
  end
end