Improve best rated selector

If user asked for two langages, we have to select the best subtitle according to the language order.

For example :
`Requested : spa, fre`

`Possible responses are ( * is the selected response ) :`

```
[spa, 0] *
[spa, 0]
```

```
[spa, 0]
[spa, 4] *
```

```
[fre, 0]
[fre, 4] *
```

```
[fre, 0]
[spa, 0] *
[spa, 0]
```

```
[fre, 0]
[spa, 0]
[spa, 4] *
```

```
[fre, 7] *
[spa, 0]
[spa, 4]
```
