RPM Support

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

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

Publish:
We will successfully publish all modulemd-defaults, even those which are missing some module stream of profile( in the repo itself). DNF-like clients are expected to fail gracefully in this case.

Upload:
We will accept a compressed yaml doc file which might have 1 or more modulemd-defaults. We will not check for the presence of the modules in the destination repo
and/or
modulemd-defualts can be created/updated via api by providing module name, stream, profiles and its' yaml doc file
NOTE : no sanity check on the modules, its' available streams/profiles will be performed during defaults creation/update
NOTE : if there is already a default defined in a repo an update will occur by overriding current values with new ones.

Copy:
just modulemd-defaults are copied. If there are already some defaults defined in the destination repo - they will be overridden.

Remove:
just modulemd-defaults are removed

Module and defaults relationship:

when a module is coped - no defaults are carried over
when a module is removed - no defaults are removed. As a result there might be 'outdated; defaults but dnf-like clients should manage this situation

tldr - module and defaults do not depend on each other.