Add support for FSharp.Json serialization library about oryx HOT 1 OPEN

        // json handler w/ FSharp.Json library
        let json<'TResult> (options: JsonConfig) (source: HttpHandler<HttpContent>): HttpHandler<'TResult> =
            let parser (stream: Stream) =
               use sr = new StreamReader(stream)
               // `ReadToEnd` can throw OOM exception. What is the best way to handle it in Oryx?
               let textJson = sr.ReadToEnd()
               Json.deserializeEx<'TResult> options textJson

            parse parser source

match ret with
                | Ok result -> return result
                | Error error -> return raise (JsonDecodeException)