lib/solr4r/client/query.rb (more_like_this_q): Updated for Solr 5.3.0.
lib/solr4r/client/query.rb (more_like_this_q): Updated for Solr 5.3.0.

* Fixes handling of multiple field names: https://issues.apache.org/jira/browse/SOLR-7143.
* Adds support for other MoreLikeThisHandler options: https://issues.apache.org/jira/browse/SOLR-7639.

blackwinter/solr4r