The path can contain the repository name (i.e. the ''key'' for retrieving the configuration data for that repository) and this should enable us to use a kind of "virtual" filesystem encompassing all the repositories.
In case there's a conflict between a path below one repository and a path below an other (for example with a path below the default repository), the longest repository name will have priority (therefore the default repository will never win).
API changes:
- added `RepositoryManager.get_repository_by_name(path, authzname)`
