Mail Queue UI module: use LazyLoaderAdapter. Refs #2042
/etc/sudoers template (20postfix): enabled postqueue and postsuper commands. Refs #2042
Mail Queue UI module: added Delete action, to expunge a single message from postfix queue. Refs #2042
Mail Queue UI module: added DeleteAll action. Refs #2042
Mail Queue UI: check external postfix commands exit status. Refs #2042
Release 1.3.0