TODO
* Investigate into thrift connection for performance better than http.
http://www.elasticsearch.org/guide/reference/modules/thrift.html
* Use optimizer to collapse nested operations.
* Push down limited and unlimited result walking to elasticsearch driver and use cursor!
* Add optimizer stage to reorder relation in a way unsupported operations are not done on gateway relation.
* Add write support once axiom has writable relations
* Use Axiom::Proxy to simplify gateway
* Fix/Workaround coredump in jruby-19mode http://travis-ci.org/#!/mbj/axiom-elasticsearch-adapter/jobs/1768119
* Push a bugreport to yard or yardstick to fix def each; super; end in Query::Unlimited and Query::Limited