Any language will do. I'm fairly well versed in any middleware technology -- Rails, Django, Java, node.js. For the presentation, I'd like to stick with Rect.js/ReactNative. So I guess, back to the language question -- combination of JS on the server and the client will do just fine. My goal is to keep it as simple as possible and really focus on what can be done with blockchain.

aren't blockchain protocols supposed to be language neutral.

that's exactly right