Fix missing 'channel' param of 403 ERR_NOSUCHCHANNEL
Fix missing 'channel' param of 403 ERR_NOSUCHCHANNEL

Spec: https://tools.ietf.org/html/rfc2812#section-5.2

(Note that, as with most other RFC numerics, there's an implied <client>
parameter, which is the only one it had before)

gitterHQ/irc-bridge,gitterHQ/irc-bridge