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


We should start thinking on more specialized exceptions. This will avoid unwanted behaviour. This will require a big refactor, but we can start thinking and even start implementing and changing when a PR request touch some file that have generic exception.