Ifeelgoods generate api route

I've added some more customization possibilities via configuration.

I've also changed removing the '()' from the path, as this probably depends on the usage and people might have different preferences that can be customized by the custom formatter: therefore I find it better to keep the info there in the base and removing it later, as the other way around, we loose the information at the beginning and we can't do anything about that in the custom formatter.

I've also change the way it handles the api_base_url, as the previous version was not working when customizing the api_base_url from resource description. After this change, it just doesn't try to modify the apis that come from the routes.

I've also removed the initial filtering base on the api_base_url (for similar reasons) and enhanced support for engines.
Perhaps should we log a warning ?