Goal: 

• Rather than having the user create a custom EPEL repository, we should have a shared repository (similar to red hat repos). This could be seen and used by any user without having to create a custom repository for EPEL.

Acceptance Criteria:

• Community repositories are returned in list and fetch calls for any org
• List can filter by community repositories only, e.g. 

  /repositories/?origin=community

• Community repositories have their own org and pulp domain
• Community repositories should be introspected and snapshotted as part of process-repos
• Add check in validation API to prevent creation of custom EPEL repos in the UI. Creation through API will be addressed separately.
• User should not be able to create, delete, or edit community repositories
• User can list packages and snapshots for community repositories, or anything a red hat repo allows