Replace the `method_attributes` and `hidden_attributes` methods with
`api_attributes`. `api_attributes` can be used as a class macro:
# include only the given attributes.
api_attributes :id, :created_at, :creator_name, ...
# include all default attributes plus the `creator_name` method.
api_attributes including: [:creator_name]
or as an instance method:
def api_attributes
[:id, :created_at, :creator_name, ...]
end
By default, all attributes are included except for IP addresses and
tsvector columns.
In xml responses, if the result is an empty array we want the response
to look like this:
<posts type="array"/>
not like this (the default):
<nil-classes type="array"/>
This refactors controllers so that this is done automatically instead of
having to manually call `@things.to_xml(root: "things")` everywhere. We
do this by overriding the behavior of `respond_with` in `ApplicationResponder`
to set the `root` option by default in xml responses.
