mattbaird/elastigo — pull request #149 by Sean-Der (2014-12-11 19:54:19+00:00)
Title: Implement Lt method on *FilterOp, Gt method on *FilterOp is now an interface{} allowing it to accept date ranges

Before Gt would only accept ints, meaning you couldn't do [this](http://www.elasticsearch.org/guide/en/elasticsearch/guide/current/_ranges.html)

Also implement Lt