fix logout bug

in the origin web site, you should do these 2 step if you wanna logout:
step 1: get
http://account.178.com/q_account.php?_act=logout&to=http://bbs.ngacn.cc/

step 2: post http://bbs.ngacn.cc/nuke.php with
func=logout&no_auto_login=1

whatever, in this case, it seem like work well without step 1.