index other_names field

Currently, `other_names` field is not indexed, so we cannot query for it (e.g. `q=other_names:"alcaligenes eutrophus"` return no hit). We should index it similar to other name fields (`common_name` and `scientific_name`):

```
"scientific_name": {
"index": true,
"searched_by_default": true,
"type": "text"
},
```
