Remove Cartridge->CartridgeRepository dependency for path setup

Feed the Cartridge object an optional 'repository_base_path' which can
be used internally for the Cartridge to construct its own repository path
without requiring a dependency upon the CartridgeRepository.

This helps maintain test and v1 path compatibility by allowing the Cartridge
objects to be instantiated absent the use of the CartridgeRepository.
Endpoint mapping support WIP