use opsworks native deploy_to and rails_env

This makes your cookbook a little more generic so it can be used by others. It removes the need for an explicit `path` and `rails_env` settings since those are [available from OpsWorks](http://docs.aws.amazon.com/opsworks/latest/userguide/attributes-json-deploy.html). So the only thing you need in your custom JSON is the `workers` attribute (used the same way as before):

```json
"resque": {
  "app-name": {
    "workers": {
      "*": 1
    }
  }
}
```

Notice above that the immediate child of `resque` is the application name. This allows you to configure resq