The repositories used by RCM never change, there is no need for them to
include checksum of the repository.
Also rework the tests as the store will change in following commits
(store now needs to include a registry of all distros because we can do
cross-distro builds)
It contains two basic endpoints:
* POST /v1/compose
* GET /v1/compose/<uuid>
It passes all the tests, but cannot be used for the intended use case
because the store API does not (yet) support distributions and
architectures as a parameters.