Plack::Middleware::JSONP - Wraps JSON response in JSONP if callback parameter is specified
enable "JSONP", callback_key => 'jsonp';
Plack::Middleware::JSONP wraps JSON response, which has Content-Type value either
application/json as a JSONP response which is specified with the
callback query parameter. The name of the parameter can be set while enabling the middleware.
This middleware only works with a non-streaming response, and doesn't touch the response otherwise.