Ensure Resource.find_first returns an object of the correct type.

pillarsdk/resource.py

@@ -191,12 +191,13 @@ class Find(Resource):
         url = utils.join_url_params(cls.path, params)
 
         response = api.get(url)
-        res = cls(response)
-        if res._items:
-            return utils.convert_datetime(res._items[0])
-        else:
+        if not response.get('_items'):
             return None
 
+        resource = cls(response['_items'][0])
+        utils.convert_datetime(resource)
+        return resource
+
     @classmethod
     def find_one(cls, params, api=None):
         """Get one resource starting from parameters different than the resource