Added features object into model by middleware

Earlier the features object set into model by middleware was a
JSON.stringified version of the features object. That made it tricky
for view engines to check status of features.

Now model gets both versions added:
Features === features object
FeaturesJSON === JSON stringified features object

This resolves #2
Bugfix for res.render() failing without model
Merge pull request #3 from phillipj/middleware/features-object

Actual features object into model from middleware