Make MoreLikeThisHandler distributable

The MoreLikeThis component, when used in the standard search handler supports distributed searches. But the MoreLikeThisHandler itself doesn't, which prevents from say, passing in text to perform the query. I'll start looking into adapting the SearchHandler logic to the MoreLikeThisHandler. If anyone has some work done already and want to share, or want to contribute, any help will be welcomed.