Elasticsearch more_like_this works with additional filters now

Alert: it needs updated pyelasticsearch also (please see my fork).

Elastiscearch backend was not handling additional_query_parameter in any way. Because of this all queries with more_like_this at the end was returning the same results.
More like this query in elasticsearch makes query itself, but according to http://elasticsearch-users.115913.n3.nabble.com/Filter-on-quot-more-like-this-quot-query-td1586714.html it is possible to add query_string parameters to it.
I have done it in the simplest way, but needed it as a hotfix.