Add cache and offload tasks

- use uwsgi cache2 as workers shared storage
- offload case create/close with uwsgi mules
- refactoring

Change-Id: I25d44e87e552d701f7851f28dba3e7ffc218399a
Related-bug: PROD-30321 (PROD:30321)
diff --git a/sf_notifier/tests/test_client.py b/sf_notifier/tests/test_client.py
index 059ea24..f505e68 100644
--- a/sf_notifier/tests/test_client.py
+++ b/sf_notifier/tests/test_client.py
@@ -2,7 +2,8 @@
 
 import pytest
 
-from sf_notifier.salesforce.client import SalesforceClient, SfNotifierError
+from sf_notifier.salesforce.client import SalesforceClient
+from sf_notifier.salesforce.exceptions import SfNotifierError
 
 
 ENV_VARS = [