add UDP protocol support for logger

When a syslog daemon fails and SysLogHandler cannot reconnect to
it, server processes (proxy, container, object, and more)
would start consuming 100 % CPU and stop responding to requests.
It is because the server process go into an infinite loop if they
fail to reconnect to /dev/log.
This problem happens only when using unix_sockets.

This change enables us to use syslog without unix_sockets and fixes bug 780025.

Change-Id: Ibcc99a1a148b1008036146bf3bd079a9be24982c

swift/proxy/server.py

@@ -1865,7 +1865,8 @@ class BaseApplication(object):
         if logger is None:
             self.logger = get_logger(conf, log_route='proxy-server')
             access_log_conf = {}
-            for key in ('log_facility', 'log_name', 'log_level'):
+            for key in ('log_facility', 'log_name', 'log_level',
+                        'log_udp_host', 'log_udp_port'):
                 value = conf.get('access_' + key, conf.get(key, None))
                 if value:
                     access_log_conf[key] = value