Update for koa v2
I took a look the current dependencies and it depends on [co-views](https://github.com/tj/co-views). co-views depends of [co-render](https://github.com/tj/co-render) which relies on [consolidate.js](https://github.com/tj/consolidate.js).

With [koa v2 supporting promises](https://github.com/koajs/koa/tree/2.0.0-alpha.3#example), I don't seen the need to use co-views, because [consolidate.js also returns promises](https://github.com/tj/consolidate.js#promises), so the new version should have a simpler implementation.

I want to know if my thoughts are in the right direction because I may find time to upgrade this modul to create a new version to be used with Koa V2.
