Add helper for lenient queries

[epelc]

It would be nice if there was an option for lenient queries without having to do custom json.

http://www.elastic.co/guide/en/elasticsearch/reference/1.x/query-dsl-query-string-query.html
Search for lenient

lenient - If set to true will cause format based failures (like providing text to a numeric field) to be ignored.

[mikeyoon]

#177 will address this once it's merged. Unfortunately, the pull request includes breaking changes, so it'll probably be a while before you can use it.

[mikeyoon]

#238 is merged now, so this should be available.