Add possibility to add settings when create doc

Add the 'settings' variable to add to options when create a doc in elastic search.

For example: 
```js
TagsSchema.plugin(elastiSearch, {
    host: ....,
    port: ....,
    settings: {
        analysis: {
            filter: {
                autocomplete_filter: {
                    type: 'edge_ngram',
                    min_gram: 1,
                    max_gram: 25
                }
            },
            analyzer: {
                autocomplete: {
                    type: 'custom',
                    tokenizer: 'standard',
                    filter: [
                        'lowercase',
                        'autocomplete_filter'
                    ]
                }
            }
        }
    }
});
```