Add parsing to MDN rules
Add parsing to MDN rules

Issue: #480

minaevmike/rspamd,minaevmike/rspamd,andrejzverev/rspamd,AlexeySa/rspamd,minaevmike/rspamd,andrejzverev/rspamd,AlexeySa/rspamd,AlexeySa/rspamd,minaevmike/rspamd,andrejzverev/rspamd,AlexeySa/rspamd,minaevmike/rspamd,andrejzverev/rspamd,minaevmike/rspamd,AlexeySa/rspamd,andrejzverev/rspamd,minaevmike/rspamd,AlexeySa/rspamd,andrejzverev/rspamd,AlexeySa/rspamd,minaevmike/rspamd,AlexeySa/rspamd,AlexeySa/rspamd,andrejzverev/rspamd,andrejzverev/rspamd,minaevmike/rspamd