Enable keepalived debug logs when debug=True

This will expose more details about what keepalived is doing (like
adding new VIPs, gARPs sent, config warnings and such).

Change-Id: I297f13f3debe0c80d1ad58f9031618fec3575ad0

neutron/agent/linux/keepalived.py

@@ -482,6 +482,8 @@ class KeepalivedManager(object):
                    '-f', config_path,
                    '-p', pid_file,
                    '-r', self.get_vrrp_pid_file_name(pid_file)]
+            if logging.is_debug_enabled(cfg.CONF):
+                cmd.append('-D')
             return cmd
 
         return callback