Keep getting error when trying to use koa-views
I have not used koa much, I have used express a bit so this may be me doing something stupid.

Anyway the error I get is:

```
TypeError: undefined is not a function
    at Object.<anonymous> (C:\Code\Web\testing\nodetest\client\app.js:23:16)
    at GeneratorFunctionPrototype.next (native)
    at next (C:\Code\Web\testing\nodetest\node_modules\koa\node_modules\co\index.js:83:21)
    at Object.<anonymous> (C:\Code\Web\testing\nodetest\node_modules\koa\node_modules\co\index.js:56:5)
    at next (C:\Code\Web\testing\nodetest\node_modules\koa\node_modules\co\index.js:99:21)
    at Object.<anonymous> (C:\Code\Web\testing\nodetest\node_modules\koa\node_modules\co\index.js:56:5)
    at Server.<anonymous> (C:\Code\Web\testing\nodetest\node_modules\koa\lib\application.js:123:8)
    at Server.EventEmitter.emit (events.js:110:17)
    at HTTPParser.parserOnIncoming [as onIncoming] (_http_server.js:504:12)
    at HTTPParser.parserOnHeadersComplete (_http_common.js:111:23)
```

The code looks like:

```
var koa = require('koa');
var router = require('koa-router');
var views = require('koa-views');

var app = koa();
var port = 3001;

app.use(router(app));

var viewsDir = __dirname + "\\views";
app.use(views(viewsDir, {
    default: 'jade'
}));

app.get('/', function *(next) {
    yield this.render('index', {});
});

console.log("Setup on Port" + port)
app.listen(port);
```

I tried swapping `this.render` to `views.render`, also just so you are sure there is a folder called views with a file called index.jade, and jade has been installed. None of the examples showed it needing to be required explicitly.

So am I doing anything crazy?

Also on a side note is Vash supported? as I was hoping to use that (as I do like Razor syntax).
