Query experiment


    $ curl "localhost:8080/increment?expId=999&armId=AAA&offers=1"
    OK
    $ curl "localhost:8080/increment?expId=999&armId=BBB&offers=1"
    OK
    $ curl "localhost:8080/increment?expId=999&armId=BBB&rewards=1"
    OK
    $ curl "localhost:8080/query?expId=999"
    {"errors":[],"results":[{"rewards":1,"offers":1,"armId":"BBB"},{"rewards":0,"offers":1,"armId":"AAA"}]}

I've heard good things about [json4s](https://github.com/json4s/json4s). Ooyala wrote a [summary](http://engineering.ooyala.com/blog/comparing-scala-json-libraries) as well.