`querystring` => `qs`, adds support for nested objects

Enables transmitting nested objects with Content-Type
`application/x-www-form-urlencoded`
support complex querystring parameters

this querystring convention is very popular with emberjs, ruby on
rails, node-express .. and probably others :)
Add tests and fix merge
Merge pull request #1315 from spumko/jmonster-qs

Use QS module for query string parsing