More customizable RoutesFormatter

Ability to specify the formatter thought the configuration and
influence the other +api+ paramters (such as desc) form the formatter.
Support for loading routes from engines

Adding a recursion for getting routes form mounted engines.

Also checking if we need to add the api_base_url to the path instead
of removing the api_base_url when loading the path from routes:
doesn't play well with inheritance of api_base_url.
Distinguish between api from routes and the others