Pulp

I have an implementation, but I made so many workarounds:
https://github.com/pulp/pulpcore/pull/514

1 - I adapted PulpPluginAppConfig for getting the serializers (2 serializers with the same model, results in dict with only the last serializer)
2 - Convert model to dict for using it on serializer
2.1 - serializers with nested serializers like DistributionTreeSerializer: https://github.com/pulp/pulp_rpm/blob/master/pulp_rpm/app/serializers.py#L1020
I'm sending an empty list on the related fields like: "addons": [], "checksums": [], ...
2.2 - SingleArtifactContentUploadSerializer needs relative_path, artifact / file, I'm sending a fake file,
but when validation requires a specific kind of file it fails. I got it here: https://github.com/pulp/pulp_rpm/blob/master/pulp_rpm/app/serializers.py#L232-L246
which I treated by avoiding deferred_validate
but I also got a problem here:
https://github.com/pulp/pulp_rpm/blob/master/pulp_rpm/app/serializers.py#L500-L513
that I could not treat

PR: https://github.com/pulp/pulpcore/pull/532