NFS exports restored as read-only - continued 1 rockstor#2912

- Add default ordering to NFSExportGroup models.
Addresses re-enabled test provoked warnings re:
"UnorderedObjectListWarning: Pagination may yield inconsistent
results with an unordered object_list"

src/rockstor/storageadmin/models/nfs_export_group.py

@@ -69,3 +69,4 @@ class NFSExportGroup(models.Model):
 
     class Meta:
         app_label = "storageadmin"
+        ordering = ['-id']

src/rockstor/storageadmin/tests/test_nfs_export.py

@@ -86,21 +86,15 @@ def setUpClass(cls):
     def tearDownClass(cls):
         super(NFSExportTests, cls).tearDownClass()
 
-    # TODO: FAIL {"detail":"Not found."}
-    # def test_get(self):
-    #     """
-    #     Test GET request
-    #     1. Get base URL
-    #     2. Get request with id
-    #     """
-    #     # get base URL
-    #     self.get_base(self.BASE_URL)
-    #
-    #     # get nfs-export with id
-    #     nfs_id = self.temp_nfsexport.id
-    #     response = self.client.get('{}/{}'.format(self.BASE_URL, nfs_id))
-    #     self.assertEqual(response.status_code, status.HTTP_200_OK,
-    #                      msg=response)
+    def test_get(self):
+
+        # get base URL
+        self.get_base(self.BASE_URL)
+
+        # get nfs-export with id
+        nfs_id = 3  # from fixture
+        response = self.client.get(f'{self.BASE_URL}/{nfs_id}')
+        self.assertEqual(response.status_code, status.HTTP_200_OK, msg=response)
 
     def test_invalid_get(self):
         # get nfs-export with invalid id