ninny support for JSON-RPC

Usage:

1. import com.lightform.mercury.json.ninny._
2. Any time a Reader[JsValue, A] or Writer[JsValue, A] is needed as an implicit parameter, just ensure you have a FromJson[A] or ToJson[A] in implicit scope. toJsonReader and fromJsonWriter imported from NinnySupport will do the conversions for you.