Expose recursion level for Hunspell token filter. Closes #3369

Allows to override recursion level for the Hunspell token filter. By default the recursion level is set to 2 which is not suitable for certain languages/dictionaries. For example for `cs_CZ` (czech) language based on OpenOffice dictionaries it gives better results with recursion level 1 or even better 0.

One can override the `recursion_level` using the following configuration:

```
{
    "filter" : {
        "type" : "hunspell",
        "locale" : "cs_CZ",
        "recursion_level" : 0  // optional, defaults to 2
    }
}
```