Default to empty strings instead of Petstore example for backwards compatibility.
The title and description are "required", so we should probably provide them instead of an empty dictionary as suggested earlier.

Thanks @ariovistus
https://github.com/marcgibbons/django-rest-swagger/pull/136#issuecomment-61758503
https://github.com/swagger-api/swagger-spec/blob/master/versions/1.2.md#513-info-object
Looks like there is a 2.0 Swagger spec present, so the 1.2 should be stable enough to document here - the URL is unlikely to break.
https://github.com/swagger-api/swagger-spec/blob/master/versions/2.0.md