Wrap update response

Wrapping the json response in a 'beer' root.

example: 

    { "beer" : {
        "_id" : "521393b10364d042526793f5",
        "name" : "dani",
        "alc" : 4.6,
        "rating" : "5",
        "tasted" : false
      }
    }

This allows the [susuba web front end](https://github.com/jugglinghobo/susuba-web-ui) to use the default RESTAdapter functionality and doesn't force it to override adapter actions for updating