Added resource test cases

Fix #365 
@naegelyd 
Signed-off-by: Sheik Hassan <solergiga@yahoo.com>
OK. To fix that you can just create it and not assign it:

```python
Assessment.objects.create(sample_result=self.result,
                                       user=self.user,
                                       assessment_category=self.category,
                                       sanger_requested=False,
                                       pathogenicity=self.pathogenicity,
                                       father_result=self.parental_result,
                                       mother_result=self.parental_result)
```