Description of problem:
Playbooks from deleted repositories still can be found in the playbooks list.

Version-Release number of selected component (if applicable):
5.8.0.7-nightly.20170328151956_0fcdb72

How reproducible:
Always

Steps to Reproduce:
1. Navigate to Automation/Ansible/Repositories.
2. Add some repositories with ansible playbooks.
3. Delete that repositories.
4. Navigate to Automation/Ansible/Credentials.

Actual results:
There are playbooks from deleted repositories.

Expected results:
Playbooks should be removed after repository deleting.