[DONOTMERGE] Augmenting existing API smoke test suite.

TL;DR Great job. Add a test?

This looks fine. :100: It could be good to add a test to [`test_entities.py`](https://github.com/omaciel/robottelo/blob/master/tests/robottelo/test_entities.py), though, as it helps to ensure the efficacy of this code. Also, I'd like to point out the importance of `path(which='this')`. Imagine, for a moment, that this was written instead:

```python
if which == 'sync':
    return super(Repository, self).path() + '/sync'
return super(Repository, self).path()
```

In this case, a user could get unexpected results:

```python
>>> Repository(id=5).path(which='sync')
'https://example.com/api/v2/repositories/5/sync'  # correct
>>> Repository().path(which='sync')
'https://example.com/api/v2/repositories/sync'  # d'oh!
```