Add wait 30s for auth error

- prevent auth requests flood (like with wrong credentials)
- makes easier log tracking

Change-Id: Id0e9c33a78d4623b08c6f5e24eb220d2c908f689
Related-bug: PROD-29246 (PROD:29246)
diff --git a/sf_notifier/salesforce/client.py b/sf_notifier/salesforce/client.py
index 95f324d..71ada18 100644
--- a/sf_notifier/salesforce/client.py
+++ b/sf_notifier/salesforce/client.py
@@ -65,7 +65,7 @@
         fcntl.flock(fd, fcntl.LOCK_EX | fcntl.LOCK_NB)
         yield
     except IOError:
-        logger.info('Waiting for session file 5 seconds...')
+        logger.info('Session file locked. Waiting 5 seconds...')
         time.sleep(5)
     finally:
         fcntl.flock(fd, fcntl.LOCK_UN)
@@ -140,8 +140,8 @@
         try:
             config.update({'session': self.session})
             self.sf = Salesforce(**config)
-        except sf_exceptions.SalesforceAuthenticationFailed:
-            logger.error('Salesforce authentication failure.')
+        except sf_exceptions.SalesforceAuthenticationFailed as ex:
+            logger.error('Salesforce authentication failure: {}.'.format(ex))
             self.metrics['sf_auth_ok'].set(0)
             return False
 
@@ -188,7 +188,7 @@
                 saved_session = self._load_session(session_file)
 
                 if self._refresh_ready(saved_session):
-                    logger.info('Attepmting to refresh session.')
+                    logger.info('Attempting to refresh session.')
 
                     if self._auth(self.config):
                         auth_success = True
@@ -202,6 +202,10 @@
                     logger.info('Not refreshing. Reusing session.')
                     auth_success = self._reuse_session(saved_session)
 
+        if auth_success is False:
+            logger.warn('Waiting 30 seconds before next attempt...')
+            time.sleep(30)
+
         return auth_success
 
     def auth(self):