Add "info" key to SWAGGER_SETTINGS

So you can configure the title, description, etc of a SwaggerResourcesView without needing to subclass it and override .get(). 

It should be easy enough to find the newly documented setting to turn it off (just pass an empty dictionary, i.e. `SWAGGER_SETTINGS = {'info': {}, ...}`) if anyone doesn't like the Petstore defaults that appear and doesn't want to add their own info to the page, i.e. wants to restore the old behaviour.