Add support for the parameters ids and docs in MoreLikeThisQuery

[ericklombardo]

See the elasticsearch reference for the more like this query:
http://www.elasticsearch.org/guide/en/elasticsearch/reference/current/query-dsl-mlt-query.html
It include those top level parameters

[Mpdreamz]

Thanks for requesting this one @ericklombardo this has now been implemented.