Create Decorators

* Match will show different elo depending on completeness
* Match completed shows elo of the time
* Match incompleted shows player's elo
Also consider writing this ias 
```
@match = find_match
decorate(@match)
```

then decorate match will be 
```ruby
def decorate_match
  unless @match.winner?
    @match  = UncompletedMatch.new(@match)
  end
end
```