RPM Support

As a result of this story it will be possible to sync, upload, publish, copy and remove modulemd

Upload:
We will accept a compressed yaml doc file which might have 1 or more modules. We will not check for the presence of the modular rpms in the destination repo

Sync:
We will parse a compressed yaml doc file which might have 1 or more modules. We will not check for the presence of the modular rpms in the destination repo

Publish:
We will successfully publish all modules, even those which are missing rpms. DNF-like clients are expected to fail gracefully in case of corrupted modules.

Copy:
Default copy will be simple copy. It will copy just the module itself. No rpms are carried over.

Remove:
Default remove will be simple remove. It will remove just the module itself. No rpms are touched.
For later: an option will be added '--recursive' which will will remove the module and it's rpms in case those rpms are not referenced in the other modules within the repo.

NOTE:

• in the pulp repo modular and not modular rpms can co-exist.
• we cannot prevent from removal of rpms which can be part of a module.