Make IRC Bot connect on both successful end of MOTD (376) and non-successful MOTD (422)

Summary: http://www.networksorcery.com/enp/protocol/irc.htm

Test Plan: augment code with an additional debug line (phlog('hi');) so I can see my case was trigged and it will fall through. setup an ill-configured IRC server with ngircd. Configure an ircbot to connect to said ill-configured IRC server. verify ircbot connected to channel. verify in irc bot logs that debug line was invoked.

Reviewers: epriestley

Reviewed By: epriestley

CC: aran, Korvin

Maniphest Tasks: T1452

Differential Revision: https://secure.phabricator.com/D2962