Implemented content-view tests

Implemented 10 CV tests:
- test_cv_associate_components_composite_negative
- test_cv_associate_puppet_repo_negative
- test_associate_view_custom_content
- test_cv_associate_composite_dupe_repos_negative
- test_cv_promote_custom_content
- test_cv_publish_custom_content
- test_cv_edit : Plan to create diff tests from this like: 
  - test_positive_cv_update_name
  - test_negative_cv_update_name
  - test_positive_cv_update_description
  - test_negative_cv_update_description


Is better to use `assertIsNotNone`?