Add "withMaxRows" and deprecate "withNumRows" on Search.Builder class [JIRA: CLIENTS-966]

[Search.Builder](http://basho.github.io/riak-nodejs-client/classes/Search.Builder.html) class has `withNumRows` method, but a parameter name is `maxRows`. I confused this mismatch of naming rule.
Is there any reason about leaving this mismatch?
