Merge pull request #24 from jwhonce/dev/wip

WIP Cartridge Refactor
Unified runtime cucumber test API

Consolidate cart operation entrypoints through ApplicationContainer and
update the runtime test API to be compatible with both V1 and V2 cart
models.

Update all cartridge manifests to be compatible with the latest cartridge
manifest spec.
Merge pull request #25 from ironcladlou/cart-refactor

Unified runtime cucumber test API
Temporary commit