Fixed jade compile issues and updated tests to verify fix.

Currently on master if try out the jade view example located in `examples/views/jade` you will loading the index view triggers a 500 error.

The first issue is the example is trying to load `.html` as jade files.

The second issue is associated with the use of `extends` in the example, to enable using shared layouts.

The message for this error is as follows:

```
Error: the "filename" option is required to use "extends" with "relative" paths
```

I have resolved this by updating the attribute used to pass the template filename to jade `lib/views.js`

Lastly I added a shared layout to the existing jade template test to ensure this doesn't crop up again.

Thanks