Log connection and network errors as warnings

Closes #71.

Author: eht16

logstash_async/worker.py

@@ -212,10 +212,10 @@ def _flush_queued_events(self, force=False):
             try:
                 events = [event['event_text'] for event in queued_events]
                 self._send_events(events)
-            # exception types for which we do not want a stack trace
+            # Log connection and network errors as warnings as they are rather harmless
             except (ConnectionError, TimeoutError, socket_gaierror) as exc:
                 self._safe_log(
-                    'error',
+                    'warning',
                     'An error occurred while sending events: %s',
                     exc)
                 self._database.requeue_queued_events(queued_events)