As an authenticated user, I can upload ansible roles into a pulp repository.
1. User uploads role version tar to /artifacts/ creating new Artifact record
2. User creates a new role by posting to /content/ansible/roles/ (optional)
3. User creates a new role version by posting to /content/ansible/roles/<uuid>/versions/. The fields would be role (href), version or version name (string), and artifact (href)
Steps 1-2 were taken care of in this PR:
Step 3 is outstanding.