locals can be passed as `views` opts

With this commit `locals` can be sent like this:

```js
var views = require('../../co-views');
module.exports = views(__dirname+'/../app/views', {
  map: { ... },
  locals: { ... } // this is needed for flexibility
});
```
This update also solves this proposal: https://github.com/visionmedia/co-views/pull/14
Please accept and merge. Thanks.