ring.util.response.ok

hi.

would love to see ```ok``` in Ring. Because:

- it's a real http status code name for 200
- shorter than ```response```
- already commonly used elsewhere (like in [Spray](http://www.w3.org/Protocols/HTTP/HTRESP.html) & [Play](http://www.playframework.com/documentation/2.0.4/api/scala/play/api/mvc/Results.html))
- first thing I write into my Ring-based web apps

regards,

Tommi