Piper/validate response url

### What is the problem / feature ?

Add validation for the response url

### How did it get fixed / implemented ?

Not sure. I forgot what's going on with this branch.

### How can someone test / see it ?

Dunno

*Here is a cute animal picture for your troubles...*

![1-christmas-animals-1-1](https://cloud.githubusercontent.com/assets/824194/5448715/3c9b37e2-84a3-11e4-8d86-682e33273f31.png)