Reuse Salesforce session id

- Session file
- One worker at a time has ability to lock session file,
  auth and write new session id
- Other workers waits and reuse the session id
- Workers compare their session id with the one in file

Change-Id: I371b0a7172a5b312a2ae2aef96d02505a1823f86
Related-bug: PROD-29347 (PROD:29347)
diff --git a/sf_notifier/tests/test_client.py b/sf_notifier/tests/test_client.py
index c6a2a2e..059ea24 100644
--- a/sf_notifier/tests/test_client.py
+++ b/sf_notifier/tests/test_client.py
@@ -32,7 +32,7 @@
             'SANDBOX_ENABLED': True
         },
         {
-            'instance': 'instance_xxx',
+            'instance_url': 'instance_xxx',
             'username': 'username_xxx',
             'password': 'password_xxx',
             'organizationId': 'org_xxx',
@@ -49,7 +49,7 @@
             'ENVIRONMENT_ID': 'env_xxx'
         },
         {
-            'instance': 'instance_xxx',
+            'instance_url': 'instance_xxx',
             'username': 'username_xxx',
             'password': 'password_xxx',
             'organizationId': 'org_xxx',