repository tests using apis

Added few positive tests for repository create/update and delete
FYI, [`test_delete_and_get`](https://github.com/omaciel/robottelo/blob/master/tests/foreman/api/test_multiple_paths.py#L431) and [`test_delete_status_code`](https://github.com/omaciel/robottelo/blob/master/tests/foreman/api/test_multiple_paths.py#L276) do basically the same thing. Is this test still necessary in that case?