352 who reply: do not warn if nick is me

Hi,

I just noticed:
2013/03/06 22:02:25 state_handlers.go:177: WARN irc.352(): received WHO reply for unknown nick xxxx

Apparently it's because of the check "if != conn.Me()" being done in the if so we fallback in the else with the warning.
The proposed change avoids this with a little refactor following effective Go's way of eliminating error cases as they arise.

Cheers,
StalkR