Add celery task to check job finished

- celery task called after countdown of 60 minutes from start of job processing

app/v2/errors.py

@@ -10,10 +10,11 @@ from app.errors import InvalidRequest
 class JobIncompleteError(Exception):
     def __init__(self, message):
         self.message = message
+        self.status_code = 500
 
     def to_dict_v2(self):
         return {
-            'status_code': 500,
+            'status_code': self.status_code,
             "errors": [
                 {
                     "error": 'JobIncompleteError',