irc: remove tag "notify_private" from notices received before message 001

This removes tag "notify_private" from notices like that (sent before message 001):

:irc.network.com NOTICE nick :*** Spoofing your IP
:irc.network.com NOTICE nick :*** You are exempt from K/G/X lines
:irc.network.com NOTICE nick :*** You are exempt from user limits
Version 0.4.1-rc2